Apparatus and method for continuous noninvasive measurement of respiratory function and events

ABSTRACT

An apparatus and method for non-invasive and continuous measurement of respiratory chamber volume and associated parameters including respiratory rate, respiratory rhythm, tidal volume, dielectric variability and respiratory congestion. In particular, a non-invasive apparatus and method for determining dynamic and structural physiologic data from a living subject including a change in the spatial configuration of a respiratory chamber, a lung or a lobe of a lung to determine overall respiratory health comprising an ultra wide-band radar system having at least one transmitting and receiving antenna for applying ultra wide-band radio signals to a target area of the subject&#39;s anatomy wherein the receiving antenna collects and transmits signal returns from the target area.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/749,861, filed Mar. 30, 2010, titled “APPARATUS AND METHOD FORCONTINUOUS NONINVASIVE MEASUREMENT OF RESPIRATORY FUNCTION AND EVENTS,”Publication No. US-2011-0060215-A1, which claims the benefit under 35U.S.C. 119 of U.S. Provisional Patent Application No. 61/164,772, filedMar. 30, 2009, titled “APPARATUS AND METHOD FOR CONTINUOUS NONINVASIVEMEASUREMENT OF RESPIRATORY FUNCTION AND EVENTS,” each of which is hereinincorporated by reference in its entirety.

This application may be related to co-pending U.S. patent applicationSer. No. 10/456,290 titled “SYSTEM AND METHOD FOR EXTRACTINGPHYSIOLOGICAL DATA USING ULTRA-WIDEBAND RADAR AND IMPROVED SIGNALPROCESSING TECHNIQUES”, filed on Jun. 2, 2003, now U.S. Pat. No.7,725,150.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates in general to respiratory monitoring. Moreparticularly, the present invention relates to an apparatus and methodfor non-invasive physiological monitoring to determine respiratory rate,rhythm, tidal volume and other functional metrics including detection ofrespiratory events and trends that may signal abnormal physiologicalfunctionality.

BACKGROUND OF THE INVENTION

Many diverse medical conditions directly affect the lungs and overallpulmonary function. Accordingly, respiratory data can provide valuableinformation concerning the existence, onset and progression of a diseaseor injury affecting a patient. Several different methods are currentlyused to monitor pulmonary or respiratory functionality. Unfortunately,existing respiratory monitoring methods are complex, inconvenient,limited in scope or simply too expensive. None lend themselves toeffective use in an ambulatory setting and instead, generally requirethat a subject be monitored in a hospital or doctor's office.

Consequently, delivery of a simple, reliable and portable apparatus tocollect desired respiratory information would be invaluable to societyand satisfy a long-felt need in the healthcare profession. The abilityto safely, easily, and accurately measure respiratory function alongwith specific intermittent events and overall trends will provide thehealthcare professional with critical information needed to provideappropriate and timely care. An apparatus that provides a reliable,simple means to measure and monitor respiratory function in conjunctionwith other physiological metrics, including heart rate, has been highlysought after. Additionally, the provision of such a device for use in anambulatory setting would enable a health care provider to gain uniqueinsight into a person's pulmonary responses to various stresses in anormal, everyday setting. This has been a long-felt need for decadeswhich others have yet been unable to satisfy.

Both qualitative and quantitative aspects of respiratory function needto be monitored to assess, diagnose and treat problematic respiratorysymptoms which may be driven by one of many respiratory, cardiac andother diseases. In particular, respiratory rate, rhythm, and, tidalvolume are important parameters commonly measured to aid a physician indetermining a patient's state of respiratory health and uncover otherconditions that might affect respiratory health. It would be highlydesirable to provide a respiratory monitoring apparatus that can easilybe used by an individual or caregiver, regardless of the individual'scurrent health status, mobility or lack thereof. In addition, it wouldbe highly desirable to provide such an apparatus that can remaincontinuously with a patient during transition within a hospital settingand subsequently during outpatient treatment. Still further, it would behighly desirable to provide such an apparatus for nonintrusive use by anindividual during normal daily routines to aid in the capture ofrespiratory events and trends which may be indicative of an adversecondition which might otherwise go unnoticed.

To understand the operation of the present invention and its utility andimportance in providing assessment of respiratory function andperformance, it will help to have a reasonable understanding of thevarious mechanical aspects of respiratory function along with thecurrent methods used to measure important respiratory metrics. Followingis a directed overview of relevant elements of respiratory function.

1. Related Art

An assessment of the mechanics of breathing deals with the movement ofthe diaphragm and associated muscles, movement of the rib-cage andassociated musculature, and, physical characteristics of the lungsthemselves. The muscular action controls breathing and it causes thevolume of the lungs to increase and decrease in order to regulate thecontent of carbon dioxide in the arterial blood. Currently, there arevarious methods used to assess the function of each breathing mechanismcomponent, however no single device is known that can easily,conveniently and accurately evaluate the overall performance ofbreathing. Existing methods used for respiratory assessment include: (1)the displacement method, which consists of wearing a chest wrap withadhesive sensors attached to it, (2) the thermistor method, whichrequires a facial mask for measuring respiration heat, (3) the impedancepneumography test, which attaches electrodes on the surface of the skinand measures chest movement, (4) the CO₂ method, which consists of acontinuous measurement of expired air and the utilization of infraredrays, and, (5) a piezoelectric external mechanical movement detectionand correlation method. It is important to note that all of the aboveapproaches fail to obtain direct information concerning the both themechanical aspects of the respiratory process and the physiologicalchanges within the lungs themselves during the respiratory process.

Certain elements of respiration may be measured directly using, forexample, external breathing masks. Breathing masks, however, aregenerally not well tolerated by patients for extended periods of time.Additionally, such masks are not convenient for ambulatory patients.Additionally, a system having one or more sensors disposed at or nearthe surface of a patient's body for monitoring physiological variablesof a patient in real time, including respiratory sounds for thedetection of abnormal breathing patterns, is generally disclosed in U.S.Pat. No. 5,738,102 issued to Lemelson.

Further, qualitative assessments of respiratory function are made viaimpedance measurements using implanted electrodes for detecting changesin thoracic impedance associated with changing lung volume duringinspiration and expiration. Tidal volume and respiration rate may beapproximated from the measured impedance. Normal changes in respirationrate and tidal volume in response to exercise are measured usingimpedance sensing in some cardiac pacemakers to provide asensor-indicated pacing rate for rate-responsive cardiac pacing. See,for example, U.S. Pat. No. 4,901,725 issued to Nappholz.

Still further, respiratory signals may be extracted from otherphysiological signals that can be obtained from implantable sensors. Forexample, physiological signals, such as subcutaneous ECG, cardiacelectrogram (EGM), blood pressure, and heart sound signals, typicallycontain cyclical amplitude changes caused by the respiratory cycle.Pulsus paradoxus refers to a decrease in arterial blood pressure thatoccurs during inspiration. A device for measuring pulsus paradoxus forassessing and monitoring patients with respiratory disease is generallydisclosed in U.S. Pat. No. 6,325,761 issued to Jay, incorporated hereinby reference in its entirety. A method for computing tidal volume as afunction of extracted blood pressure information indicative of thechange in blood pressure that occurs over a respiratory cycle isgenerally disclosed in U.S. Pat. No. 5,980,463, issued to Brockway, etal. Implantable cardiac rhythm management or cardiac monitoring devicesmay sense ECG, EGM, blood pressure and/or other physiological signalsthat vary due to the influence of respiration.

Each of the above existing methods is relatively complex, expensive andsomewhat invasive. They do not lend themselves to use outside a hospitalor doctor's office. It would be advantageous and beneficial to providean apparatus capable of monitoring the desired parameters more simplyand noninvasively, in a manner that allows continuous use in essentiallyany location.

2. Respiratory Metrics

Monitoring and assessment of lung function is an indispensable tool fordiagnosing and monitoring respiratory disease states, along with theroot causes of the current respiratory state or other diseasesassociated with the respiratory state. There are several key respiratoryfunctional metrics that are considered when assessing an individual'srespiratory health. FIG. 1 is a chart illustrating the relationshipbetween the various standard metrics. A first metric is an individual'stotal lung capacity, which is a cumulative measure of the additionalmetrics of inspiratory reserve volume, including tidal volume,expiratory reserve volume, and residual volume. Inspiratory reservevolume is the additional air that can be inhaled after a normal tidalbreath in. Tidal volume is the normal volume of air breathed in and out.Expiratory reserve volume is the amount of additional air that can bebreathed out after the end expiratory level of normal breathing.Residual volume is the amount of air left in the lungs after a maximalexhalation, i.e., the amount of air that is always in the lungs and cannever be expired.

Measuring an individual's total lung capacity can provide criticalbackground information about a person, and, needs to be considered inmaking diagnoses. An individual's total lung capacity typically dependson such factors as the person's age, height, weight, and sex. Total lungcapacity normally ranges between 4 to 6 liters. Females tend to have a20-25% lower total lung capacity than males. Tall people tend to have alarger total lung capacity than shorter people. Smokers tend to have alower total lung capacity than nonsmokers. Lung capacity can also beaffected by altitude. People who are born and live at sea level willtypically have a smaller lung capacity than people who spend their livesat a high altitude.

In addition to measuring total lung capacity, one also measures tidalvolume, the volume of air breathed in with an average breath. Tidalvolume is typically between 0.5 to 1 liters. Measurement of tidal volumeand changes or trends in tidal volume provides critical diagnostic dataconcerning pulmonary function and performance. For example, typicalresting adult respiratory rates are 10 to 20 breaths per minute withapproximately a third of the breath time involved in inspiration. Humanlungs, to a certain extent, are overbuilt and have a tremendous reservevolume as compared to the normal oxygen exchange requirements when anindividual is at rest. For example, individuals can smoke for yearswithout having a noticeable decrease in lung function while still ormoving slowly. For example, although total lung capacity may be between4 to 6 liters, with tidal volume between 0.5 to 1 liters, only a smallportion of the total lung capacity is typically in use, approximatelybetween 8% to a maximum of 25%. While in a resting state, only a smallportion of the lungs are actually perfused with blood for gas exchange.As oxygen requirements increase due to exercise, a greater volume of thelungs is perfused, allowing the body to reach its CO₂/O₂ exchangerequirements. Hence, the smoker engaged in exercise will most likelyexperience an oxygen deficit due to existing damage to the lungs whichprevents perfusion of a greater volume of the lung area.

It would be advantageous to provide a convenient, small apparatus andsensor capable of both qualitatively and quantitatively measuring thevarious pulmonary functional parameters including respiratory rate,respiratory rhythm, tidal volume, and, total lung capacity, along withother calculable and derivative parameters such as vital capacity andresidual volume, among others. It would also be advantageous to providesuch an apparatus capable of measuring changes in perfusion in each lobeof one or both lungs.

3. Respiratory Metrics of Primary Respiratory Diseases

Respiratory diseases can generally be categorized as obstructive,restrictive, parenchymal, vascular or infectious. Following is a briefoverview of these respiratory disease types relevant to the applicationof the present invention.

Obstructive lung diseases (OLD) are characterized by an increase inairway resistance, evidenced by a decrease in Peak Expiratory Flow Rate(PEFR) measured in spirometry by the Forced Expiratory Volume in 1Second (FEV1). The Residual Volume, the volume of air left in the lungsfollowing full expiration, is greatly increased in OLD, leading to theclinical sign of chest over-inflation in patients with severe disease.Many patients with chronic OLD present with “barrel chest”—a deformityof outward rib displacement due to chronic over-inflation of the lungs.Patients with OLD typically have ‘large, floppy lungs’. In ObstructiveLung Disease, the lung volume (Total Lung Capacity, TLC), Vital Capacity(VC), Tidal Volume (VT) and Expiratory Reserve Volume (ERV) remainrelatively unchanged. It would be advantageous to provide a simple,noninvasive apparatus and sensor that could monitor and track chestover-inflation and lung size in conjunction with the other functionalpulmonary metrics to assess the onset and progression of OLD in patientsin a continuous manner. Some notable obstructive lung diseases whichcould be more competently assessed through the provision and use of suchan apparatus and sensor include emphysema, bronchitis, asthma, chronicobstructive pulmonary disease, bronchiectasis, bysssinosis,bronchiolitis, and, asbestosis.

Restrictive lung diseases (RLD) are characterized by a loss of airwaycompliance, causing incomplete lung expansion (i.e. via increased lung‘stiffness’). This change manifests itself in reduced Total LungCapacity, Inspiratory Capacity and Vital Capacity. In contrast to OLD,RLD values for Tidal Volume, Expiratory Reserve Volume, FunctionalResidual Capacity and Respiratory Volume are unchanged. It would beadvantageous to provide a simple, noninvasive apparatus and sensor thatcould monitor and track changes in total lung capacity, inspiratorycapacity and vital capacity along with other pulmonary metrics to assessthe onset and progression of RLD in patients in a continuous manner.Notable restrictive lung diseases which could be more competentlyassessed through the provision and use of such an apparatus and sensorinclude fibrosis, sarcoidosis, pleural effusion, hypersensitivitypneumonitis, asbestosis, pleurisy, lung cancer, infant respiratorydistress syndrome (IRDS), acute respiratory distress syndrome (ARDS),neurologic diseases affecting the ability of the body to alterrespiration rate including spinal cord injury, mechanical diseasesaffecting pulmonary musculature including myasthenia gravis, and, severeacute respiratory syndrome (SARS).

Parenchymal lung disease is characterized by damage to the lungs whichmay be caused by environmental or other factors. The basic functionalunits of the lung, the alveoli, are referred to as the lung parenchyma.Chronic obstructive pulmonary disease (COPD), also known as chronicobstructive airway disease (COAD), is a group of diseases characterizedby the pathological limitation of airflow in the airway that is notfully reversible. COPD is the umbrella term for chronic bronchitis,emphysema and a range of other lung disorders. It is most often due totobacco smoking, but can be due to other airborne irritants such as coaldust, asbestos or solvents, as well as congenital conditions. Diseasessuch as COPD are characterized by destruction of the alveoli and aretherefore referred to as parenchymal lung diseases. Signs of parenchymallung disease include, but are not limited to, hypoxemia (low oxygen inthe blood) and hypercapnoea (high carbon dioxide in the blood). Inaddition, parenchymal lung diseases can present with symptoms ofelevated respiratory rate with corresponding reduced tidal volume.Chronic complications of parenchymal lung disease include reducedrespiratory drive, right ventricular hypertrophy, and right heartfailure (cor pulmonale). Notable parenchymal diseases include COPD,sarcoidosis, pulmonary fibrosis, and, emphysema. It would beadvantageous to provide a simple, noninvasive apparatus and sensor thatcould continuously and directly monitor respiratory rate incorrespondence with changes in tidal volume in conjunction with theother functional pulmonary metrics to assess the onset and progressionof parenchymal lung diseases in patients.

Vascular lung disease refers to conditions which affect the pulmonarycapillary vasculature. Alterations in the vasculature manifest in ageneral inability to exchange blood gases such as oxygen and carbondioxide, in the vicinity of the vascular damage (other areas of the lungmay be unaffected). Signs of vascular lung disease include, but are notlimited to, hypoxemia (low oxygen in the blood) and hypercapnoea (highcarbon dioxide in the blood). Chronic complications of vascular lungdisease include reduced respiratory drive, right ventricularhypertrophy, and right heart failure (cor pulmonale). In addition,parenchymal lung diseases can present with symptoms of elevatedrespiratory rate with corresponding reduced tidal volume. For example,pulmonary hypertension, a vascular lung disease, is an increase in bloodpressure in the pulmonary artery, pulmonary vein, or pulmonarycapillaries, together known as the lung vasculature, leading toshortness of breath, dizziness, fainting, and other symptoms, all ofwhich are exacerbated by exertion. Notable vascular lung diseasesinclude pulmonary edema, pulmonary embolism, and, pulmonaryhypertension. It would be advantageous to provide a simple, noninvasiveapparatus and sensor that could continuously and directly monitorrespiratory rate indicating breathlessness and tidal volume inconjunction with the other functional pulmonary metrics to assess theonset and progression of vascular lung diseases in patients.

Infectious lung diseases are typically caused by one of many infectiousagents able to infect the mammalian respiratory system, for example, thebacterium Streptococcus pneumoniae. The clinical features and treatmentoptions vary greatly between infectious lung disease sub-types as eachtype may be caused by a different infectious agent, with differentpathogenesis and virulence. Features also vary between upper respiratorytract infection, including strep throat and the common cold; and lowerrespiratory tract infection, including pneumonia and pulmonarytuberculosis. Lower respiratory tract infections place a considerablestrain on the health budget and are generally more serious than upperrespiratory infections. Since 1993 there has been a slight reduction inthe total number of deaths from lower respiratory tract infection.However in 2002 they were still the leading cause of deaths among allinfectious diseases accounting for 3.9 million deaths worldwide and 6.9%of all deaths that year.

These infectious lung diseases typically present with symptoms ofshortened breath resulting in a corresponding increase in respiratoryrate. It would be advantageous to provide a simple, noninvasiveapparatus and sensor that could continuously and directly monitorrespiratory rate and tidal volume in conjunction with the otherfunctional pulmonary metrics to assess the onset and progression ofinfectious lung disease in patients.

Respiratory tumor can refer to either neoplastic (cancerous) ornon-neoplastic masses within the lungs or lung parenchyma. Respiratoryneoplasms are abnormal masses of tissue within the lungs or parenchymawhose cell of origin may or may not be lung tissue (many other neoplasmscommonly metastasize to lung tissue). Respiratory neoplasms are mostoften malignant, although there are non-malignant neoplasms which canaffect lung tissue. Respiratory neoplasms include mesothelioma, smallcell lung cancer, and, non-small cell lung cancer. Each of thesetypically present with symptoms of shortness of breath. Consequently, itwould be advantageous to provide a simple, noninvasive apparatus andsensor that could continuously and directly monitor respiratory rate andtidal volume thereby assessing shortness of breath, in conjunction withthe other functional pulmonary metrics, to allow assessment of the onsetand progression of infectious lung diseases in patients.

4. Respiratory Metrics and Indicators of Cardiac Failure

Measurement of pulmonary functionality and performance can be atremendous aid in identifying symptoms associated with cardiac problems.For example, congestive heart failure (CHF) is a condition that canresult from any structural or functional cardiac disorder that impairsthe ability of the heart to fill with or pump a sufficient amount ofblood through the body. Congestive heart failure is often undiagnoseddue to a lack of a universally agreed definition and difficulties indiagnosis, particularly when the condition is considered “mild”. Evenwith the best therapy, heart failure is associated with an annualmortality of 10% (Stefan Neubauer (2007). “The failing heart—an engineout of fuel”. N Engl J Med 356 (11): 1140-51). It is the leading causeof hospitalization in people older than 65. (McKee P A, Castelli W P,McNamara P M, Kannel W B (1971). “The natural history of congestiveheart failure: the Framingham study”. N. Engl. J. Med. 285 (26):1441-6.)

The symptoms of congestive heart failure depend largely on the side ofthe heart exhibiting predominant failure. If both sides are functioninginadequately, symptoms and signs from both categories may be present.Given that the left side of the heart pumps blood from the lungs to theorgans, failure to do so leads to congestion of the lung veins andsymptoms that reflect this, as well as reduced supply of blood to thetissues. The predominant respiratory symptom is shortness of breath onexertion, dyspnea (or, in severe cases at rest) along with becomingeasily fatigued. Orthopnea is increasing breathlessness on reclining,measured in the number of pillows required to lie comfortably.Paroxysmal nocturnal dyspnea (PND) is a nighttime attack of severebreathlessness, usually several hours after going to sleep. Poorcirculation to the body leads to dizziness, confusion and diaphoresis(excessive sweating) and cool extremities at rest. It is most closelyassociated with congestive heart failure. PND is often relieved bysitting upright, but not as quickly as simple orthopnea. Also unlikeorthopnea, it does not develop immediately upon laying down.Consequently, it would be highly advantageous to provide a non-invasive,convenient sensor that could be comfortably worn by an individual toassist in the identification of changes in respiratory rate and rhythmthat may suggest the onset of congestive heart failure, when anindividual is active, recumbent or asleep.

Paroxysmal nocturnal dyspnea (PND) is caused by increasing amounts offluid entering the lung during sleep and filling the small, air-filledsacs in the lung, the alveoli, which are responsible for absorbingoxygen from the atmosphere for exchange with blood. This fluid typicallyrests in the legs (peripheral edema), causing swelling in the legtissues during the day when the individual is upright. At night, whenrecumbent for an extended period, this fluid is reabsorbed, increasingtotal blood volume and blood pressure, leading to pulmonary hypertension(high blood pressure) in people with underlying left ventriculardysfunction. The pulmonary hypertension leads to the accumulation offluid in the lungs, or pulmonary edema. Pulmonary edema is swellingand/or fluid accumulation in the lungs. It leads to impaired gasexchange and may cause respiratory failure. It is due to either failureof the heart to remove fluid from the lung circulation (“cardiogenicpulmonary edema”), or due to a direct injury to the lung parenchyma(“noncardiogenic pulmonary edema”). Treatment depends on the cause, butfocuses on maximizing respiratory function and removing the cause. Itwould be highly advantageous to provide a non-invasive, convenientapparatus and sensor that could be comfortably worn by an individual toassist in the identification of changes in fluid in the lungs andalveoli that may suggest the onset of congestive heart failure, when anindividual is active, recumbent or asleep.

The right side of the heart pumps blood returned from the tissues to thelungs to exchange CO₂ for O₂. Hence, failure of the right side leads tocongestion of peripheral tissues. This may lead to peripheral edema oranasarca and nocturia (frequent nighttime urination when the fluid fromthe legs is returned to the bloodstream). Anasarca (“extreme generalizededema”) is a medical symptom characterized by widespread swelling of theskin due to effusion of fluid into the extracellular space. In moresevere cases, ascites (fluid accumulation in the abdominal cavity) andhepatomegaly (painful enlargement of the liver) may develop.

Heart failure may decompensate easily; this may occur as the result ofany intercurrent illness (such as pneumonia), but specificallymyocardial infarction (a heart attack), anemia, hyperthyroidism orarrhythmias. These place additional strain on the heart muscle, whichmay cause symptoms to rapidly worsen. Excessive fluid or salt intake(including intravenous fluids for unrelated indications) and medicationthat causes fluid retention (such as NSAIDs and thiazolidinediones) mayalso precipitate decompensation.

5. Respiratory Metrics and Indicators of Other Pathological Conditions

Respiratory events or disturbances may be associated with a number ofpathological conditions. Various respiratory metrics will provideindicators of these pathological conditions. For example, Cheyne-Stokesrespiration is the waxing and waning of respiration associated withcongestive heart failure. Kussmaul breathing is rapid deep breathingassociated with diabetic ketoacidosis. Central or obstructive forms ofsleep apnea are prevalent in both normal and heart failure populations.Detection of those respiratory events may be useful in monitoring apatient's disease status, selecting treatment and monitoring itseffectiveness. It would be highly advantageous to provide anon-invasive, convenient apparatus and sensor that could be comfortablyworn by an individual to assist in the identification of theserespiratory events or disturbances when an individual is active,ambulatory, recumbent or asleep.

Sleep apnea is a typically chronic condition that can serve as thecatalyst for several different pathological conditions. Respiratorydisturbances in the form of sleep-related disordered breathing may oftengo undetected in patients suffering from heart failure or sleep apnea.Nocturnal Cheyne-Stokes respiration, a form of central sleep apnea,occurs frequently in patients with chronic heart failure. The presenceof sleep apnea significantly worsens the prognosis for a heart failurepatient. A method for determining the cardiac condition of a patient bya cardiac monitor using the variability of a respiration parameter isgenerally disclosed in U.S. Pat. No. 6,454,719 issued to Greenhut,incorporated herein by reference in its entirety. Characteristics ofperiodic breathing patterns, such as hyperpnea length, apnea length, andperiodic breathing cycle length, are correlated to circulatory delaytime, which is inversely correlated with cardiac output. Therefore,recognizing and monitoring the presence of disordered breathing in heartfailure patients could provide useful diagnostic and prognosticinformation. Moreover, detecting respiratory disturbances and extractingspecific parameters related to cardiac function could provide valuableinformation for assessing a patient's cardiac condition and optimizingtherapeutic interventions. Consequently, it would be highly beneficialto provide a simple apparatus and sensor capable of noninvasivelymonitoring respiratory rate, rhythm and periodic events to identify anddiagnose conditions during a person's sleep which might be indicative ofcardiac complications or disturbances, particularly sleep apnea.

A standard approach for diagnosis of sleep apnea includespolysomnography, which requires the patient to stay overnight in ahospital for observation, in addition to medical history and screeningquestionnaires. Polysomnography involves monitoring of multipleparameters including electroencephalography, electromyography,electrocardiography, oximetry, airflow, respiratory effort, snoring,body position and blood pressure.

Polysomnography or a controlled sleep study, which can be used toidentify sleep apnea, measures a patient's respiratory patterns during asingle sleeping period. However, this procedure is expensive andinconvenient for the patient. Furthermore, a physician must activelyprescribe the sleep study and therefore must already suspect asleep-related breathing disorder. Chronic monitoring of respiratorydisturbances as an alternative to polysomnography, particularly in heartfailure patients who have increased risk of morbidity in the presence ofsleep apnea, is desirable for detecting unrecognized and unsuspectedsleep-related disordered breathing. Providing a single, simple apparatusand sensor capable of monitoring the majority of these parameterswithout having to resort to a complex configuration of sensors andwithout requiring an overnight stay at a hospital would be highlybeneficial to patients and would increase the ability of healthcareproviders to more readily identify those persons actually suffering fromsleep apnea by collecting the necessary data in their own home settingwhile sleeping in their own bed, while also substantially reducing thecosts associated with this diagnosis.

Diabetes is another disease which may be assessed via effectivemonitoring of respiratory metrics. Diabetic patients can also benefitfrom continuous monitoring of their pulmonary functionality andperformance. For example, diabetic ketoacidosis may be the first symptomto appear in a person with Type I diabetes. Diabetic ketoacidosisdevelops when blood is more acidic than body tissues due to theaccumulation of ketones in the blood when body fat is metabolized forenergy in place of glucose reserves when insulin is not available.Persons having Type II diabetes usually develop ketoacidosis only underconditions of severe stress. Recurrent episodes of ketoacidosis indiabetic persons are generally the result of poor compliance withdietary restrictions or self-administered treatments. Kussmaulbreathing, characterized by relatively deep breathing, is a commonsymptom of ketoacidosis. Therefore early detection and monitoring ofKussmaul breathing in diabetic patients may be valuable in the effectivecontrol of diabetes. Consequently, providing diabetic patients with asimple, easy-to-use, non-invasive respiratory apparatus and sensor inaddition to devices to measure blood glucose may prove highly beneficialin allowing diabetic patients to more adequately control their diabeticconditions to minimize negative symptoms and effects.

Heart failure and lung failure frequently go hand-in-hand, and hence,this condition can be assessed via effective respiratory monitoring. Aspreviously indicated, heart failure typically presents with symptoms ofshortness of breath or elevated respiration rate, among other things.Consequently, it would be extremely beneficial to provide persons with asimple, noninvasive apparatus and sensor that could continuously anddirectly monitor respiratory rate and rhythm in conjunction with theother functional pulmonary metrics to assess the onset and progressionof potential congestive heart failure in patients. In particular, itwould be extremely advantageous to provide such a device for elderlypatients most susceptible to congestive heart failure. Further, it wouldbe highly advantageous to provide such a device for use by persons whohave undergone cardiac surgery to continuously monitor respiratory rateand rhythm to provide tangible evidence to the patient that the surgerywas successful, thereby reducing anxiety concerning future potentialheart failure. It would be still further advantageous to provide such adevice that can simultaneously monitor both cardiac and pulmonary rateand rhythm to provide a more meaningful assessment and correlationbetween changes in either cardiac or pulmonary functionality.

In light of the plethora of pulmonary diseases which may be morecompetently assessed via the use of an effective respiratory measurementdevice, and, given the correlation between respiratory function andcardiac health, it would be highly desirable to provide a wearabledevice that can detect advanced respiratory functions, is non-invasive,does not require surgery for implantation, does not require skincontact, conductive gels or electrode patches, does not require wearingan uncomfortable band wrapped around the chest, is low power without anyionizing radiation, allows long-term continuous patient monitoring inboth hospital and ambulatory settings, is safe, allows real-time 24/7monitoring, and is more affordable than current techniques and devices.It would be further highly desirable to provide such a device capable ofsimultaneously monitoring both cardiac and respiratory functionality.The present invention is directed to providing the above desiredfeatures which have been long sought after by healthcare providers.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method for non-invasive,instantaneous and continuous measurement of a subject's respiratoryrate, rhythm, volume and other functional and physiological pulmonarymetrics for the purposes of detecting respiratory trends, events ordisturbances related to a pathological condition. The apparatus may beused as a medical diagnostic device or used for non-medical purposes,such as athletic performance monitoring.

In particular, the present invention provides an apparatus and methodthat is uniquely capable of monitoring each individual lobe of each lungsimultaneously. The apparatus is preferably self-contained and usedexternally. A sensing portion of the apparatus, the “sensor”, generatesan output signal that varies with the respiration cycle such that arespiration rate, rhythm and optionally other respiration features maybe derived or extracted from the sensed signal. The apparatus includesone or more of these sensors placed about the thorax or abdomen of asubject to collect data relevant to respiratory performance andfunctionality. Each sensor comprises an ultra wide-band radar systemhaving a transmitting and receiving antenna for applying ultra wide-bandradio signals to a target area of the subject's anatomy wherein thereceiving antenna collects returns from the target area. The receivedsignals are then delivered to a data processing unit such as anintegrated processor, a PDA or Personal Computer, having software andhardware used to process the signal returns to generate resultsindicating respiratory performance or status.

The signal data is provided as an input to one or more physiologicalassessment algorithms, including a respiratory assessment algorithm. Themethod of the respiratory assessment algorithm generates relevantmeasures of respiratory rate, rhythm, tidal volume, and other pulmonaryparameters and respiratory events and disturbances. In addition, in oneembodiment, the algorithm generates an ongoing and continuous trend ofpotential congestion or fluid buildup in the lungs themselves bycorrelating the measured bulk dielectric strength of targeted areas ofthe lungs to assess and quantify both instantaneous fluid content andchanges in fluid content. The apparatus and methods of the inventiondetermine if the data indicates the presence of symptoms associated withvarious diseases: respiratory, cardiac and others. The algorithms areimplemented in the apparatus or in associated external systems and canprovide various alerts to caregivers to allow rapid response to seriousimmediate events, and, can provide trending data for use by a physicianto assess changes in a patient's pulmonary performance which mayindicate a need for various treatments. The apparatus may be applied inboth ambulatory and non-ambulatory settings.

In one aspect of the present invention, an apparatus is provided thatincludes a control unit, an antenna, and a sensing unit capable ofresolving a change in a spatial configuration of a lung during arespiration cycle, and, is capable of measuring respiration rate, rhythmand tidal volume, along with other derivative respiratory metrics.

In another aspect of the present invention, a method is provided thatincludes receiving a reflected signal originally transmitted fromoutside a subject's body and directed at the subject's thoracic area anddetermining a change in a dimension of portions of the lungs during arespiration cycle, based upon the transmitted and reflected signal.

In yet another aspect of the present invention, an apparatus and methodis provided that includes an external sensor that transmits signals intoa subject's thoracic area to determine changes in dielectric strength ofmonitored portions of each lung so as to determine if a subject may beprogressing toward a congestive state suggesting imminent congestiveheart failure.

In a further aspect of the present invention, an apparatus and method isprovided that includes multiple sensors which monitor and compareexcursion of each individual lobe of each lung so as to determinewhether any obstructions exist within associated bracchii. These andother aspects of the present invention are described in additionaldetail in the remainder of this document. It should be understood,however, that the description herein of specific aspects, versions orembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

For example, described herein are devices and apparatus for determininga change in the spatial configuration of a lung by interrogating thelung with electromagnetic energy. These devices or apparatus mayinclude: at least one antenna adapted to be located adjacent a portionof the lung; and a sensing unit capable of resolving a change inreflected signals, wherein said sensing unit of the apparatus is capableof resolving a change in reflected signals that are functionally relatedto a change in respiratory volume.

The apparatus may be configured for location external to the body. Insome variations, the sensing unit further comprises: a substrate and atleast two antennae mounted to said substrate in a pattern and beingcapable of both transmitting and receiving radiofrequency signals. Thereflected signals may be derivative of an earlier transmitted ultrawide-band signal. The reflected signals may be derivative of an earliertransmitted ultra wide-band signal having a frequency band extendingfrom 3.1 GHz to 10.6 GHz, ensuring compliance with applicable FCCregulations.

The device may be adapted to collect data from at least one lung, orform more than one lung. For example, the apparatus may be adapted tocollect said data from a targeted portion of at least one lung. Thetargeted portion may be any of the upper, middle or lower lobes of atleast one lung and said targeted portion is encompassed by aninterrogation volume and said interrogation volume encompasses arespiratory chamber.

Also described herein are medical devices for assessing pulmonaryfunctionality comprising: a sensing unit including a control unit, aradar transceiver, and at least one antenna, said at least one antennabeing adapted to be located adjacent a portion of a lung to measuredynamic motion of a targeted portion of the lung. The control unit maydrive the radar transceiver and the radar transceiver may transmitsradiofrequency energy at said targeted portion and said radartransceiver receives reflections from said targeted portion and said atleast one antenna couples the radiofrequency energy between saidtransceiver and said targeted portion.

The sensing unit further comprises software configured to cause saidsensing unit to be capable of resolving a change in a spatialconfiguration of the lung. The change in spatial configuration may befunctionally related to a change in lung volume.

In some variations, the sensing unit further comprises: a substrate;said at least one antenna mounted to said substrate and being capable ofsensing a reflected signal; and a plurality of conductors extending fromsaid at least one antenna and electrically coupled with said controlunit. The sensing unit may further comprise: a substrate; at least twoantennae mounted to said substrate in a pattern and being capable ofsensing reflected signals received by said at least two antennae; and aplurality of conductors extending from said at least two antennae andelectrically coupled with said sensing unit.

The at least one antenna may be adapted to be located on a subject'schest adjacent a portion of at least one lung. The at least one antennamay be adapted to be located in close proximity to the sternum within athree centimeter radius of a center of the sternum so as tosimultaneously collect reflected signals caused by the beating of theheart and internal movement derivative of respiration.

Also described herein are non-invasive systems for determining dynamicphysiologic and structural anatomic data from a subject comprising anultra wide-band radar system having at least one transmitting antennaand at least one receiving antenna for applying ultra wide-band signalsto a target area of the subject's anatomy adjacent the lungs whereinsaid receiving antenna collects and transmits signal returns from saidtarget area which are then delivered to a data processing and controlunit having software and hardware used to process said signal returns toproduce a value for said dynamic physiologic and structural anatomicdata concerning behavior of the lungs.

The ultra wide-band signals may be transmitted in a manner compliantwith FCC regulations in a frequency spectrum from 3.1 GHz to 10.6 GHz.The dynamic physiologic and structural anatomic data is related torespiratory function. The dynamic physiologic and structural anatomicdata may be related to a change in the spatial configuration of at leastone lung. The dynamic physiologic and structural anatomic data may berelated to a change in the spatial configuration of at least one lobe ofat least one lung. The dynamic physiologic and structural anatomic datamay be related to respiratory function and provides an assessment ofchanges in any of respiratory rate, respiratory rhythm, and tidalvolume. The dynamic physiologic and structural anatomic data may berelated to respiratory function and provides a quantitative assessmentof lung volume and respiratory output.

Also described herein are methods for determining changes in respiratoryvolume in a body wherein an ultra wide-band medical radar transceiver,including a transmitter and a receiver and a signal processor integratedwith software elements in conjunction with a central processing unit areused according to the following steps: said transceiver transmits aseries of extremely short duration electromagnetic pulses into a body,said electromagnetic impulses encounter a boundary between differentbiological substances in the body, small amounts of incident energyencountering the boundary are reflected back towards said receiver asraw reflections where said raw reflections are captured andpre-processed by said receiver, said receiver captures a plurality ofsaid raw reflections using a high speed sample and hold circuit wherecapture time for a sample of said raw reflections is set equal to around trip time of flight from said transmitter to a depth range ofinterest and back to said receiver, said plurality of sampledreflections from said depth ranges of interest are integrated to form anintegrated signal to minimize high frequency noise so as to avoidcorruption of desired data related to tracking instantaneous respiratorychamber volume, said integrated signal is amplified and passed through alow-pass filter to prevent signal aliasing prior to digitization, apredetermined number of reflections for a first range of interest arecollected and integrated, said receiver sample timing is changed andreflections from a next range of interest are captured, said above stepsare repeated until reflections from an entire range of interest acrossthe respiratory chamber are collected, said above step is thencontinually repeated to deliver an updated instantaneous measure ofrespiratory volumetric changes.

The boundaries within a target range of interest may move with respectto placement of said transceiver's antenna, producing a complex seriesof time-varying reflections, and wherein said complex series oftime-varying reflections are continually processed by said signalprocessor to extract information on the mechanical activity of at leastone lung.

The signal processor and central processing unit may provide calculationof respiratory chamber volume via the additional steps of: saiddigitized radar reflections are first range aligned on sweep boundariesand passed through a series of high pass filters to minimize lowfrequency noise and static clutter, resultant data associated with allanatomical motion in said range of interest is amplified and coarsequantized using a binary quantizer where the quantizer threshold for agiven sweep or row is based on the median value of the data set,resulting in an intermediate black and white image, said intermediateimage is further refined through the application of a series of one ormore 1-dimensional or 2-dimensional filters to reduce noise to removerandom speckle noise and increase the sharpness of the image boundaryedges, supporting accurate determinate of spatial change, and, therebypresenting an image space full of various spatial structures changing intime that represent both lung wall motion and various noise sourcesincluding organs, bones, and stray radiofrequency emissions.

The data may be further refined via the application of at least oneadditional metric to delineate and confirm that the structures found inthe image are lung wall excursions and not caused by unrelated signalsources.

The at least one additional metric is respiratory rate wherein therespiratory rate is integrated within said signal processor and isdetected via application and processing of the UWBMR signals, saidsignal processor calculating the respiratory rate via conversion of anentire swept image space to a predetermined frequency domain using analgorithm, wherein said algorithm identifies and isolates an imageregion of the swept range containing the strongest respiratory signal,while simultaneously determining a range of depth containing thetargeted respiratory motion for use in determining one or moreadditional metrics.

The method may also include the steps of: wherein said at least oneadditional metric is identification and verification of completeness ofa target respiratory structure as the respiratory structure changes overtime, by evaluating the sustained and rhythmic behavior of therespiration-influenced anatomical elements, wherein the IRV identifiesqualifying signals for further analysis by capturing and prioritizingthose said qualifying signals with respect to minimum discontinuities,and wherein a conversion process includes a chain coding technique inconjunction with at least one structural morphological technique tominimize signal discontinuities caused by noise loss.

The method may further include: wherein said at least one additionalmetric is the continual and repeated identification and tracking of arespiratory-like motion characteristic in the candidate image space,wherein said respiratory-like motion characteristic best characterizesthe approximate motion of the anterior and posterior respiratory chamberwalls through time, and, wherein a corollary component of saididentification and tracking of said respiratory-like motioncharacteristic is the isolation and avoidance of signals having anon-respiratory-like motion characteristic, wherein saidnon-respiratory-like motion signals indicate the likely presence of anon-respiratory signal source.

The method may further include: wherein said at least one additionalmetric is the development of a correlation between the time-domaincharacteristics of the isolated respiratory range bin identified by afirst respiratory rate metric with points identified in the image spacethat represent minimum, maximum, and zero-crossing points of respiratorywall excursions in the image space as identified by a second and a thirdmetric.

The method may also include: wherein said data is further refined viathe application of at least one additional metric to delineate andconfirm that the structures found in the image are respiratory wallexcursions and not caused by other signal sources, and wherein imageregions that meet the requirements of the at least one additional metricare isolated and identified as qualifying candidates for furtheranalysis, wherein the likely image region providing a most probablerepresentation of the instantaneous respiratory volume is the imageregion having the strongest characteristic in said at least oneadditional metric.

The method may also include: wherein the likely image region is chosen,minimum and maximum respiratory wall excursions are identified andquantified using prior data acquired and already available from theassessment of at least one additional metric, wherein the actual chamberwall displacement is calculated using minimum and maximum respiratorywall excursions by counting spatial pixels traversed from a minimumpoint to a maximum point of a respiratory waveform to determine a countof spatial pixels traversed and multiplying said count of pixels by aresolution of the data capture device.

The instantaneous respiratory volume may be determined by the additionalstep of applying presumed dimensions of the respiratory chamber inconjunction with said minimum and maximum respiratory wall excursions todetermine volumetric changes in the respiratory chamber.

The presumed dimensions of the respiratory chamber may be represented byone or more different shapes, wherein said shapes determine the accuracyof the calculated respiratory chamber volume and the derivative tidalvolume.

The one or more different shapes is a simple elongated rectangular boxhaving dimensions approximating dimensions of a lung. The one or moredifferent shapes is an asymmetric changing ellipsoid.

The one or more different shapes may be the actual shape of saidrespiratory chamber as determined by other precursor imaging and sizingmethods, including any of x-ray, magnetic resonance imaging, ultrasound,surgery or other similar methods capable of determining the dimensionsof said respiratory chamber.

The one or more respiratory performance parameters may be determined.The one or more respiratory performance parameters may include tidalvolume, said tidal volume calculated by taking the difference betweensaid maximum and said minimum respiratory chamber volume over a singlerespiration cycle. The one or more respiratory performance parametersmay be respiratory output, said respiratory output calculated bymultiplying said tidal volume by the respiratory rate. The one or morerespiratory performance parameters may be respiratory efficiency, saidrespiratory efficiency calculated by dividing said tidal volume by amaximum respiratory chamber volume.

Also described herein are non-invasive systems for determining dynamicphysiologic and structural anatomic data from a subject comprising anultra wide-band radar system having a transmitting and receiving antennafor applying ultra wide-band signals to a target area of a subject'sanatomy wherein said receiving antenna collects signal returns from thetarget area which are then delivered to a data processing and controlunit having software and hardware used to process said signal returns toproduce a value for respiratory tidal volume and changes in respiratorytidal volume supporting multiple diagnostic requirements.

The ultra wide-band radar system may comprises a transceiver having animpulse transmitter and a swept-range receiver wherein said transmittergenerates a series of ultra wide-band pulses and said receiver capturesresulting reflections across a target range of interest and a signalprocessor operates on said range-dependent reflections to extractdesired data. The target range of interest may be located in a chestcavity, including at least one respiratory chamber. The desired data maybe instantaneous respiratory chamber volume. The desired data may betidal volume.

Also described herein are methods for detecting a respiratorydisturbance, comprising: sensing a physiological signal containing afrequency or an amplitude component related to at least two respiratorycycles; deriving at least one respiratory parameter from the physiologicsignal; and detecting a respiratory disturbance event when the at leastone respiratory parameter meets or exceeds a predetermined criteriathreshold for detecting the respiratory disturbance.

The method may also include measuring the magnitude of a characteristicof the respiratory disturbance. A measure of the respiratory disturbancemay be at least a one of: apnea duration; hypopnea duration; hyperpneaduration; a periodic breathing cycle length; a dielectric value. Thephysiological signal may be a UWB signal indicating at least a one of:respiratory rate, respiratory rhythm, tidal volume, blood pressure,patient motion, patient inactivity, cardiac rate, cardiac rhythm, and,respiratory dielectric.

The respiratory disturbance may comprise Kussmaul breathing. Therespiratory disturbance may be Cheyne-Stokes respiration. Therespiratory disturbance is sleep apnea. The respiratory disturbance isindicative of the onset of congestive heart failure.

The method may also include a step of determining an estimate of cardiacfunction based on a metric of the respiratory disturbance. The methodmay also include a step of triggering the storage of physiological dataupon the detection of the respiratory disturbance. The method may alsoinclude a step of triggering a therapy based at least in part upondetection of the respiratory disturbance. The method may also include astep of generating a warning to alert a clinician or a patient upondetection of the respiratory disturbance.

Also described herein is a device for detecting a respiratorydisturbance, comprising: means for sensing a physiological signalcontaining a frequency component or an amplitude component related to acommon characteristic of at least two respiratory cycles; means forderiving at least one respiratory parameter from the physiologic signal;and means for detecting a respiratory disturbance event when the atleast one respiratory parameter meets or exceeds a predeterminedcriteria threshold for detecting the respiratory disturbance.

Also described herein is a computer readable medium for storing a set ofcomputer instructions for performing the following method: instructionsfor sensing a physiological signal containing a frequency component oran amplitude component related to a common characteristic of at leasttwo respiratory cycles; instructions for deriving at least onerespiratory parameter from the physiologic signal; and instructions fordetecting a respiratory disturbance event when the at least onerespiratory parameter meets or exceeds a predetermined criteriathreshold for detecting the respiratory disturbance.

The computer-readable medium may also include instructions for measuringthe magnitude of a characteristic of the respiratory disturbance. Ameasure of the respiratory disturbance may be at least a one of: apneaduration; hypopnea duration; hyperpnea duration; a periodic breathingcycle length; respiratory dielectric congestion duration.

The physiological signal may be at least a one of: respiratory rate;respiratory rhythm; tidal volume; blood pressure; patient motion;patient inactivity; cardiac rate; cardiac rhythm; respiratorydielectric; an oxygen saturation measurement.

The respiratory disturbance may comprise Kussmaul breathing, aCheyne-Stokes respiration event, a sleep apnea event, a heart failureevent, a congestive heart failure event, or the like.

The method (or computer readable medium) may also include a step ofinstructions determining an estimate of cardiac function based on ametric of the respiratory disturbance; and/or instructions fortriggering the storage of a physiological data item upon the detectionof the respiratory disturbance; and/or instructions for triggering atherapy based at least in part upon detection of the respiratorydisturbance; and/or instructions for generating a warning to alert aclinician or a patient of the detection of the respiratory disturbance;and/or instructions for determining a heart failure status of a patientin the event that the estimate of cardiac function is lower than apredetermined lower threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

For fuller understanding of the present invention, reference is made tothe accompanying drawings numbered below. Where reference numbers areprovided, commonly used reference numbers identify the same orequivalent parts of the claimed invention throughout the severalfigures.

FIG. 1 is a chart illustrating the relationship between variousrespiratory metrics as measured by various embodiments according to thepresent invention;

FIGS. 2 and 3 are illustrations of a multi-sensor version of theapparatus directed toward measuring respiratory-influenced anatomicalmovement according to the present invention;

FIG. 4 is an illustration of basic operation of the apparatus accordingto the present invention;

FIG. 5 is a block diagram of primary components of the apparatus,according to the present invention;

FIG. 6 is a perspective view of a single sensor version of theapparatus, according to the present invention;

FIG. 7 is a top view of the single sensor version of the apparatus ofFIG. 6, according to the present invention;

FIG. 8 is a side view of the apparatus of FIG. 6, according to thepresent invention;

FIG. 9 is a bottom view of the apparatus of FIG. 6, according to thepresent invention;

FIG. 10 is an illustration of a single sensor version of the apparatushaving sternum-centric placement, according to an embodiment of thepresent invention;

FIG. 11 is an illustration of a single sensor version of the apparatushaving waistband-centric placement, according to an embodiment of thepresent invention;

FIG. 12 is a front view of a multiple sensor version of the apparatusworn in a vest and belt configuration, wherein each sensor communicateswirelessly to a central device, according to an embodiment of thepresent invention;

FIG. 13 is a front view of a multiple sensor version of the apparatuswherein each sensor communicates via wired links to a central device,according to an embodiment of the present invention;

FIG. 14 is a back view of the multiple sensor version of the apparatusof FIG. 13, according to an embodiment of the present invention;

FIG. 15 is a top view of a multiple sensor version of the apparatus ofFIG. 13, according to an embodiment of the present invention;

FIG. 16A is a cross-sectional view of an individual's chest cavity withmultiple sensors, according to an embodiment of the present invention;

FIG. 16B is a magnified view of that portion of FIG. 16A, defined by thecircumferential line 16B-16B, illustrating the interrogation of multipletissue interfaces by a single sensor, according to an embodiment of thepresent invention;

FIG. 17 is a front view of a multiple sensor lobe centric version of theapparatus illustrating parenchymal lung obstruction detection, accordingto an embodiment of the present invention;

FIG. 18 is front view of a multiple sensor lobe-centric version of theapparatus illustrating pulmonary congestion detection, according to anembodiment of the present invention;

FIG. 19 is a perspective view of a Bowtie antenna model, according tothe present invention;

FIG. 20 is a perspective view of an SEE antenna model, according to thepresent invention;

FIG. 21 is a chart illustrating the typical amplitude of a transmittedsignal, according to an embodiment of the present invention;

FIG. 22 is a chart illustrating the typical spectrum of the transmittedsignal of FIG. 21, according to an embodiment of the present invention;

FIG. 23 is an exemplary FDTD model of the chest cavity without lung orheart with a bow-tie antenna, according to an embodiment of the presentinvention;

FIG. 24 is a chart illustrating a simulated received signal without lungor heart, according to an embodiment of the present invention;

FIG. 25 is a chart illustrating corresponding magnitude and phase of thesimulated received signal of FIG. 24, according to an embodiment of thepresent invention;

FIG. 26 is an FDTD model of the chest cavity including the heart with abow-tie antenna, according to an embodiment of the present invention;

FIG. 27 is a chart illustrating a simulated received signal with theheart and lungs, according to an embodiment of the present invention;

FIG. 28 is a chart illustrating corresponding magnitude and phase of thesimulated received signal of FIG. 27, according to an embodiment of thepresent invention;

FIG. 29 is a plot of a simulated time domain difference signalcalculated by subtracting data derived from the test case with the heartand lungs from data derived from the test case without the heart andlungs, according to an embodiment of the present invention;

FIG. 30 is a plot of the simulated corresponding spectrum of the timedomain difference signal illustrated in FIG. 29, according to anembodiment of the present invention;

FIG. 31 is flow chart illustrating the process and algorithm of thepulmonary image quantizer of the apparatus, according to an embodimentof the present invention;

FIG. 32 is a flow chart illustrating the process and algorithm of thepulmonary boundary motion detector and metric determination algorithm ofthe apparatus, according to an embodiment of the present invention;

FIG. 33 is an illustration of the user interface of the software forreal-time pulmonary trace isolation according to an embodiment of theinvention;

FIG. 34 is an illustration of the user interface of the software forpost-processing pulmonary waveform isolation according to an embodimentof the invention;

FIG. 35 is an illustration of an isolated respiratory trace generated bythe software and algorithms according to an embodiment of the invention;

FIG. 36 is a table comparing basic correlated dielectric strength innormal and congested lungs, according to an embodiment of the invention;

FIG. 37 is a table illustrating progressive dielectric strength acrossfour congestive states, according to an embodiment of the invention;

FIG. 38 is a table illustrating progressive dielectric strength acrossfour states using multi-lobe sensors, according to an embodiment of theinvention;

FIG. 39 is a table derived from the table of FIG. 38, measured at fullinspiration only, according to an embodiment of the invention;

FIG. 40 is a combined bar and line chart illustrating the dielectricrelationship of a normal respiratory cycle using multi-lobe sensorsaccording to an embodiment of the invention;

FIG. 41 is a line chart of basic aggregate correlation of respiratorydielectric progression toward congestion and heart failure of a subjectaccording to an embodiment of the invention;

FIG. 42 is a combined bar and line chart illustrating multi-lobe sensorrespiratory dielectric progression toward congestion and associateddielectric trends, according to an embodiment of the invention;

FIG. 43 is a combined bar and line chart illustrating multi-lobe sensorrespiratory dielectric progression toward congestion and associateddielectric trends as measured at lung inflation, according to anembodiment of the invention;

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The reader is notified that the techniques described in this paper areexamples only. The description is drawn to particular embodiments,versions or aspects of the present invention. Those embodiments,versions or aspects, however, should not be read as limiting the scopeof the invention. The invention is defined legally by the claims thatissue. For example, claims may not include all the features described inconjunction with an embodiment; in that case, the claim is broader thanthe embodiment. Likewise, claims may include different combinations fromdifferent embodiments. Those having ordinary skill in the art willrecognize that changes can be made to the embodiments listed herewithout departing from the spirit and scope of the disclosure and thespirit, scope, and legal coverage of the claims.

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming and capital-intensive but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure. Now, in greater detail,embodiments of the apparatuses and methods comprising the presentinvention are described.

Different embodiments of this disclosure involve the following concepts:(1) anatomical element movement measurement using single or multiplesensors or sensor arrays; (2) anatomical element movement detectionusing a single sensor; (3) respiratory chamber interrogation using asingle sensor; (4) respiratory chamber interrogation using multiplesensors or sensor arrays; (5) respiration rate and rhythm determinationvia measurement of diaphragmatic movement using a single sensor; (6)respiration rate and rhythm determination using a chest-centric singlesensor; (7) wireless sensor array deployed in an article of clothing;(8) wired sensor array; (9) hybrid wireless/wired sensor array; (10)linear sensor arrays; (11) obstruction location determination using amulti-lobe sensor array; (12) variable adaptive lung models andalgorithms; (12) sensors to support concurrent cardiac and pulmonaryassessment; (13) sensor targeting functionality; (14) adaptive modelingand simulations methods; (15) instantaneous respiratory volume modelingand methods; (16) adaptive software user interfaces; (17) congestiveheart failure progression using a multi-lobe sensor array to trackrelative dielectric values; (18) methods for assessing respiratorychamber excursion distance; (19) methods for identifying and respondingto respiratory disturbances or events; and, (20) methods for performingparameter measurement cross-checks to confirm sensor operation andcalibration.

1. Anatomical Element Movement Measurement Using Multiple Sensors orSensor Arrays

The present invention uses electromagnetic energy in the form of uniqueradiofrequency waveforms to acquire signals indicating certainrespiratory metrics or parameters. In particular, the present inventionmeasures internal mechanical movement and dielectric strength to measureand assess various respiratory parameters.

Embodiments of the present invention provide for determining pulmonaryfunctionality and, thus, for assisting in identifying symptoms anddelivering solutions for problems associated with pulmonaryfunctionality. The present invention supports the provision of variousresponses by caregivers to modify a subject's respiratory behavior orperformance. The present invention provides information which maycomprise part of a treatment protocol to support a decision to initiateor make a change in medications to a subject to alter respiratoryfunction or to treat another disease which is suspected as the proximatecause of the abnormal respiratory behavior. Moreover, the presentinvention provides information supporting a decision to perform surgeryon a subject to rectify a critical respiratory condition, or, otherconditions which may be the proximate cause of respiratory deficiencies,such as congestive heart failure.

FIG. 1 is a chart illustrating the relationship of various parametersand metrics associated with a respiratory cycle. The present inventionanalyzes and processes measured reflected ultra-wideband (UWB) signalsto generate data used to determine the value of these various parametersand metrics for a monitored subject. These metrics include, at aminimum, respiratory rate and rhythm. Tidal volume and other metrics canbe derived from the signals received by the apparatus of the presentinvention.

In a first embodiment, as illustrated in FIGS. 2 and 3, the apparatus 10of the present invention captures and measures the motion of multipleanatomical elements during a respiratory cycle, where the motion isinduced by various types of breathing. One or more sensors 20 transmitsignals toward target areas and capture reflected signals which are thenprocessed by the sensor to develop a qualitative and quantitativeassessment of respiratory performance and health. To understand theoperation of the apparatus 10 of the present invention, it is helpfulfor the reader to understand fundamental aspects of the physiologicalmechanics of breathing and how the apparatus 10 uniquely evaluates andtracks movement of the anatomical structure to generate various relevantrespiratory parameters or metrics. The subsequent discussion ofbreathing mechanics, taken in conjunction with the respiratory diseaseinformation provided in the Background section of this document, willprovide an understanding of both the operation of the apparatus 10 ofthe present invention and how the apparatus 10 figures prominently anduniquely in the assessment of the various disease states and respiratoryperformance.

FIGS. 2 and 3 provide an illustration of the key anatomical elementsinvolved in a respiratory cycle, including inspiration and expirationrespectively. In addition, FIGS. 2 and 3 illustrate a first embodimentof the apparatus 10 of the present invention comprising the placement ofa plurality of sensors 20 about an individual's chest, abdomen and backto measure the actual anatomical mechanical movement and displacement ofanatomical elements that come into play during respiration. The presenceand integration of multiple sensors 20 will allow the apparatus to trackand monitor movement of a plurality of anatomical elements, and, tointegrate the measurement of the movement of those elements into anoverall assessment of respiratory performance.

In a first embodiment, the apparatus 10 is suited to tracking at leastthree primary types of breathing: (1) chest (or costal—meaning “of theribs”); (2) abdominal (diaphragmatic); and, (3) clavicular. In thisfirst embodiment, the apparatus 10 of the present invention primarilymeasures physiological parameters and anatomical motion associated withthe first two primary types of breathing: chest and abdominal breathing.The third primary type, clavicular breathing, characterized by shouldermovement, generally only comes into play when a person is taking amaximum breath. Although the apparatus 10 is not, in the presentconfiguration, intended to track or measure shoulder movement, anyassistance provided by clavicular breathing is reflected in the motionof anatomical elements associated with chest and abdominal breathing.Consequently, the apparatus 10 is able to also identify presence ofclavicular breathing by detection of changes in the motion of anatomicalelements associated with chest and abdominal breathing. In a derivativeembodiment to measure clavicular motion, additional sensors may bepositioned slightly higher to directly measure motion of the clavicle.

Now, in greater detail, referencing FIGS. 2 and 3, the apparatus 10comprises one or more sensors 20A through 20F deployed about a subject'supper body, including the thorax and abdomen, to measure mechanicalmotion of anatomic elements or physiological function associated withrespiration. Chest or costal breathing during inspiration I, asillustrated in FIG. 2, is primarily characterized by an outward, upwardmovement A of the chest wall C. Sensor 20A, preferably located adjacentthe midpoint of a subject's sternum, is positioned to continuouslymeasure this type of movement. Simultaneously, the diaphragm D moves ina downward direction B, expanding the volume within the chest cavity andallowing the lungs L to expand, creating a lower pressure within thelungs L and causing air to be inhaled I. Movement of the diaphragm D ismonitored by sensors 20B and 20C. Additionally, ribs R elevate and swingupward an angular distance a. This angular rotation of the ribs ismonitored by sensors 20D, 20E and 20F.

During expiration, as illustrated in FIG. 3, chest breathing ischaracterized by an inward and downward movement A′ of the chest wall Cfor a distance D2, along with a corresponding upward expansion of thediaphragm D for a distance D1, causing a greater pressure in the lungsthen the external ambient pressure and causing exchanged carbon dioxidein the lungs L to be expired E. Additionally, during expiration E, theribs R swing downward an angular distance a′.

In chest breathing, expansion of the upper torso is generally centeredat the midpoint of the chest C; it therefore tends to aerate the middlepart or lobe of each lung L most. Sensor 20A is preferably positionedadjacent the midpoint of the sternum to track the motion of the chestwall C and to sense the aeration of the middle part of each lung L. Thelower lobe of each lung L is most abundantly perfused with blood;consequently, the effort associated with chest breathing creates aventilation/perfusion mismatch. Thus, during resting periods, chestbreathing is less efficient than abdominal breathing since abdominalbreathing will tend to aerate the lower lobe having the greatestconcentration of blood perfused throughout the lung tissue. Subsequentdescribed embodiments of the present invention include sensors 20 whichdetect and measure this ventilation/perfusion mismatch by directlytracking the dielectric value of each lobe of each lung L.

The apparatus 10 of the present invention is uniquely suited tocontinually monitoring respiratory function of a subject to providequalitative measures of that subject's mental or emotional state. Forexample, chest breathing, as compared to abdominal breathing, requiresmore work to be done in lifting the rib cage, thus the body must workharder to accomplish the same blood/gas mixing than with abdominalbreathing. The greater the work expended to breathe, the greater theamount of oxygen needed, which necessarily results in more frequentbreaths. Chest breathing is useful during vigorous exercise butgenerally does not come into play for ordinary, everyday activity. Sinceit is part and parcel of the fight or flight response, it occurs whenthe individual is aroused by external or internal challenges or danger.Additionally chest breathing or the absence thereof may be precipitatedby the ingestion of various stimulants or depressants, indicating thatan individual has taken some form of drug or consumed alcohol. As aresult, chest breathing is likely to be associated with other symptomsof arousal like tension and anxiety. Since there is a reciprocalrelationship between breathing and the mind, chest breathing, ifcontinued during rest periods, will lead to tension and anxiety, thuscreating a vicious circle. With chest breathing, the breath is likely tobe shallow, jerky and unsteady, resulting in unsteadiness of the mindand emotions. Until chest breathing is replaced by deep, even and steadyabdominal breathing, efforts to relax the body, nerves and mind will beless effective. The apparatus 10 of the present invention provides anindividual with a simple, noninvasive apparatus 10 and one or moresensors 20 to distinguish chest breathing from abdominal breathing fordiagnostic, biofeedback, drug/alcohol monitoring and other purposes.

With further reference to FIG. 2, abdominal or diaphragmatic breathingis characterized by downward contraction B of the diaphragm muscles Dduring inspiration I and by upward expansion B′ of the diaphragm musclesD during expiration E. The diaphragm D, the principal muscle involved inabdominal breathing, is a strong dome-shaped sheet of muscle thatseparates the chest cavity from the abdomen. When we breathe in, thediaphragm D contracts and pushes downwards in a general direction B,causing the frontal abdominal muscles to relax and rise. In thisposition, the lungs L expand, creating a partial vacuum, which allowsair to be drawn in. When we breathe out, the diaphragm D relaxes andmoves upward in a general direction B′, the abdominal muscles contractand air containing exchanged carbon dioxide is then expelled from thelungs L. Studies indicate that the diaphragm D travels a small distanceD1 of only 1 to 2 cm during a typical respiration cycle. Sensors 20B and20C are positioned so as to track the movement of the diaphragm D duringa respiratory cycle. Sensor 20B is generally located at the front of thestomach at the waist level, supporting tracking of the movement of theforward or anterior portion of the diaphragm D; sensor 20C is locatedadjacent the small of the back, supporting tracking of the movement ofthe rear or posterior portion of the diaphragm D.

Of the two major types of breathing, abdominal breathing is consideredthe most efficient because greater expansion and ventilation occurs inthe lower part of the lung L where the blood perfusion is greatest. Inchildren and infants, the diaphragm D is effectively the sole muscle forrespiration, so watching an infant breathing provides a goodillustration of what abdominal breathing is like. As the diaphragm Dcontracts, it also pushes the abdominal organs downwards and forwards,and this rhythmical massage gently compresses the organs and improvescirculation. Abdominal breathing in conjunction with physical and mentalrelaxation has been found to reduce high blood pressure and anxiety.Consequently, the apparatus 10 of the present invention may be used toprovide a biofeedback solution to train an at-risk individual to focuson abdominal breathing whenever high blood pressure or general anxietyis present.

Assessing the type of breathing can qualitatively determine a person'smental and physical state. When an individual is calm and composed, thebreathing is typically abdominal. Since there is a reciprocalrelationship between breathing and the mind, practising abdominalbreathing leads to mental relaxation. Consequently, abdominal breathingis an important tool available for stress management. It promotes anatural, even movement of breath which calms the nervous system andrelaxes the body. Abdominal breathing is the most efficient method ofbreathing, using minimum effort for maximum oxygen. Abdominal breathingprovides the body with sufficient oxygen, expels carbon dioxideadequately, relaxes the body and the mind, and, improves circulation tothe abdominal organs. The apparatus 10 of the present inventioncomprising sensors 20 provides a noninvasive and nonintrusive, wearablerespiration monitoring apparatus 10 to distinguish chest breathing fromabdominal breathing. This information may be used for diagnostic,biofeedback and other purposes.

As previously indicated, calavicular breathing is only significant whenmaximum air is needed, such as during exercise. The name is derived fromthe motion of the two clavicles or collar bones which are pulled upslightly at the end of maximum inhalation, expanding the very top of thelungs L. It comes into play when the body's need for oxygen is verygreat. This type of breathing can be seen in patients with asthma orchronic bronchitis. The present invention provides a noninvasive,nonintrusive, wearable respiration monitoring apparatus 10 todistinguish clavicular breathing from chest breathing and abdominalbreathing. Upper sensors 20D may be targeted toward monitoring andmeasurement of movement of the clavicles to identify when a person isexperiencing clavicular breathing. This information may be used fordiagnostic and other purposes.

Now, in greater detail, as illustrated in FIGS. 2 and 3, sensors 20D,20E and 20F are preferably positioned at locations along the side ofone's chest C to track muscular and skeletal movement during arespiratory cycle. In particular, the sensors 20D, 20E and 20F track thecyclical movement of the rib structures R to assess breathing activity,particularly, respiratory rate and rhythm. In quiet respiration, thefirst and second pairs of ribs are fixed by the resistance of thecervical structures; the last pair, and through it the eleventh, by thequadratus lumborum. The other ribs are elevated, so that the first twointercostal spaces are diminished while the others are increased inwidth. Elevation of the third, fourth, fifth, and sixth ribs leads to anincrease in the antero-posterior and transverse diameters of the thorax;the vertical diameter is increased by the descent in a general directionB of the diaphragmatic dome D so that the lungs L are expanded in alldirections except backward and upward. Elevation of the eighth, ninth,and tenth ribs is accompanied by a lateral and backward movement,leading to an increase in the transverse diameter of the upper part ofthe abdomen; the elasticity of the anterior abdominal wall allows aslight increase in the antero-posterior diameter of this part, and inthis way the decrease in the vertical diameter of the abdomen iscompensated and space provided for its displaced viscera. Expiration iseffected by the elastic recoil of its walls and by the action of theabdominal muscles, which push back the viscera displaced downward by thediaphragm D. The sensors 20 of the apparatus 10 deployed about anindividuals upper torso capture reflections associated with the abovemovements. These reflections are then processed to create a measure ofrespiratory rate and rhythm, along with measurement of the change inrespiratory volume during a respiration cycle.

With continued reference to FIGS. 2 and 3, during deep respiration, allthe movements of quiet respiration also occur during deep respiration,but to a greater extent. Hence, the apparatus 10 of the presentinvention distinguishes quiet respiration from deep respiration bymeasuring the increased movement of the anatomical elements. In deepinspiration I, the shoulders and the vertebral borders of the scapulæare fixed and the limb muscles, trapezius, serratus anterior,pectorales, and latissimus dorsi, are called into play. The scaleni arein strong action, and the sternocleidomastoidei also assist when thehead is fixed by drawing up the sternum and by fixing the clavicles. Thefirst rib is therefore no longer stationary, but, with the sternum, israised; with it all the other ribs except the last are raised to ahigher level. In conjunction with the increased descent in a generaldirection B of the diaphragm D, this provides for a considerableaugmentation of all the thoracic diameters which is measured by allsensors 20 from different perspectives. The anterior abdominal musclescome into action so that the umbilicus is drawn upward and backward, butthis allows the diaphragm D to exert a more powerful influence on thelower ribs; the transverse diameter of the upper part of the abdomen isgreatly increased and the subcostal angle α opened out. The deepermuscles of the back, including the serrati posteriores superiores andthe sacrospinales and their continuations, are also brought into action;the thoracic curve of the vertebral column is partially straightened,and the whole column, above the lower lumbar vertebrae, drawn backward.This increases the antero-posterior diameters of the thorax and upperpart of the abdomen and widens the intercostal spaces. Deep expiration Eis effected by the recoil of the walls and by the contraction of theantero-lateral muscles of the abdominal wall, and the serratiposteriores inferiores and transversus thoracis. The apparatus 10captures this increased movement to identify that an individual is indeep respiration. Derivative embodiments of the present inventioninclude additional sensors 20 placed at strategic locations along anindividual's back to monitor the movement of anatomical elements in theperson's back which contribute additional data which is processed andanalyzed by the apparatus 10.

2. Single Sensor Interrogation and Assessment of Target Area

FIG. 4 is an illustration of the basic operation of the apparatus 10 ofthe present invention. The apparatus 10 comprises at least one sensor 20having a transmit antenna 30 and a receive antenna 40. A respiratorysensor module 50 controls the signals S transmitted by the transmitantenna 30. The respiratory sensor module 50 causes the transmit antenna30 to transmit electromagnetic energy in the form of an ultra-widebandradiofrequency signal S toward a target area T. The transmitted signalsS form an interrogation volume 60 which encompass a respiratory chamberof interest 70. A portion of the transmitted electromagnetic energy isreflected by the target area T and the reflections S′ are then receivedby the receiving antenna 40. The received reflected electromagneticsignals S′ are then processed by the respiratory sensor module 50.

FIG. 5 is a simplified block diagram of the respiratory sensor module 50of the sensor 20. The respiratory sensor module 50 comprises a powermodule 52 supporting an ultra-wideband medical radar module (UWBMR) 54for transmitting and receiving ultra-wideband radio signals tointerrogate a target area T of interest. The UWBMR 54 coordinates signaldelivery and reception via the transmit antenna 30 and receive antenna40. A microprocessor control module 56 manages the signals S transmittedby the UWBMR 54 and receives and processes the signals S′ delivered bythe UWBMR 54 which have been collected via the receive antenna 40. Adigital input/output module 58 delivers the processed signals from themicroprocessor control module 56 to external devices (not shown) forstorage, reporting or further processing. The input/output module 58also delivers instructions to trigger various alarms intrinsic to thesensor 20 for local announcement of certain conditions to a user orcaregiver.

Now, in greater detail, in a preferred embodiment, the apparatus 10 ofthe present invention comprises an active imaging technology composed ofthree primary elements, an respiratory sensor 20, a transmitter 30, areceiver 40, and, a respiratory sensor module 50. The respiratory sensormodule 50 comprises hardware and software elements integrated to providea stand-alone configuration. An ultra-wideband medical radar component(UWBMR) 54 drives the delivery and reception of radiofrequency signalsS, S′. The microprocessor 56, and, one or more proprietary algorithms,cooperate to drive the UWBMR 54 and measure, track and displayinstantaneous and trended respiratory function and events. The sensor 20in one configuration comprises a low-PRF (pulse repetition frequency)transmitter 30 and a swept-range receiver 40 where the transmitter 30generates a series of UWB pulses S and the receiver 40 captures theresulting reflections S′ from across a target range of interest T, suchas across a patient's chest cavity, including one or more respiratorychambers 70. In another configuration, the transmitter 30 comprises animpulse transmitter. The signal processor 56 operates on therange-dependent reflections S′ to extract desired data, includinginstantaneous respiratory chamber volume and its derivative metricsincluding tidal volume, respiratory output, and derivative respiratoryrate and rhythm.

As shown in FIG. 4, in one version, the apparatus 10 comprises anintegrated device consisting of a sensor 20 having a transmittingantenna 30 and a receiving antenna 40. The sensor 20 further includes arespiratory sensor module 50 which can be programmed to address specificailments or respiratory conditions. This architecture allows a medic touse a single base device 20 with a variety of dedicated modules forspecific medical applications. The apparatus 10 of the present inventionsupports the deployment of a low-cost sensor 20 based upon UWB signalsintegrated with a respiratory sensor module 50 with advanced softwarecapable of displaying respiratory function results to a user. Therespiratory sensor module 50 is preferably integrated within the sensor20, but may also be connected to the sensor 20 through an expansion busport on the sensor 20. The expansion bus port is an industry standardinput/output interface that allows compliant devices to work with thesensor 20. To minimize processor loading on the sensor 20, the externalrespiratory sensor module 50 will contain a dedicated embedded processor56 responsible for controlling the UWB radar 54 and processing receiveddata. In another version, a self-contained respiratory sensor module 50includes a wireless telecommunications module capable of transmittingcontinuous data to other sites, or, sending alerts or alarms to entitieswhenever a suspicious condition is detected by the apparatus 10.

3. Single Sensor Housing and Component Configuration

FIGS. 6-9 are illustrations of a preferred embodiment of the sensor 20.The sensor 20 is comprised of a plastic casing 22 to house the hardwarecomponents of the apparatus 10. The housing 22 of the sensor will restcomfortably on a subject's chest and fit comfortably in the hand of acaregiver, while the caregive is using the sensor 20 to monitor apatient's condition. As illustrated in FIG. 4 and FIG. 5, the casing 22houses antennas 30, 40 and respiratory sensor module 50. The casing 22includes a top portion 23 having a concave recess 24 for receiving astrap for securing the sensor 20 to an individual's torso. The casing 22includes slots 25 for emitting an audible acoustic signal to alert auser of the apparatus 10 of certain events or trends. A data and powerport 26 is provided in the casing 22 of the sensor 20. An off/on light21 is provided to notify a user when the sensor 20 is operational andpower is being supplied to the components. The sensor 20 includes abottom 28 of the casing 22.

FIG. 7 provides a top view of the sensor 20 and casing 22. The sensor 20includes three LED lights 27 for providing visual signals to a userduring operation of the apparatus 10, signaling certain conditions orevents. The LED lights 27 are deployed in the top 23 of the casing 22.In addition, the sensor 20 includes an LED light 21 in the top 23 of thecasing 22 to signal whether the sensor 20 is operating.

FIG. 8 provides a side profile view of the casing 22 of the sensor 20.The casing 22 is shaped such that the top 23 comfortably conforms to theshape of a user's hand when the sensor 20 is gripped and held againstthe subject's chest rather than secured to the subject's chest with astrap. During operation, a bottom 28 of the sensor casing 22 is placedadjacent the subject's chest so as to orient and place the transmitantenna 30 and receive antenna 40 in close proximity to the surface ofthe subject's chest. This profile also provides a configuration thatwill allow a first responder to provide compressions to a subject incardiac distress while simultaneously tracking the quality of thosecompressions along with associated cardiac and respiratory performance.The surface area of the bottom 28 of the casing 22 is sufficient tominimize point loading on a person's sternum while a caregiver or firstresponder is administering compressions to resuscitate a subject incardiac or pulmonary distress.

FIG. 9 provides an end view of the casing 22 of the sensor 20. Thecasing 22 includes a data/power port 26 for both receiving electricalpower from an external source to operate the components of the sensor20, and, for communicating data to an external source or for receivingdata from an external source, which might include control signals. Theend view shown in FIG. 9 also illustrates the profile of the recess 24in the top 23 of the casing 22. In use, the sensor 20 of the apparatus10 may be either held adjacent a subject's chest by a caregiver,attached with a strap, attached with some form of adhesive or held in apocket of a shirt, vest or other article of clothing, simply laid on thesubject's chest when they are in a recumbent position, or, incorporatedwith other devices, such as a defibrillator or EKG.

4. Chest-Centric Single Sensor for Cardiopulmonary Measurement andTracking

FIG. 10 is an illustration of a preferred application and embodiment ofthe apparatus 10 comprising a single sensor 20 secured to a subject'schest which enables simultaneous tracking of both cardiac and pulmonaryfunctionality. The sensor 20 includes a transmitter, 30, receiver 40 andrespiratory sensor module 50. The apparatus 10 comprises a single sensor20, placed on a subject's chest and preferably located within a3-centimeter radius G measured from the center of a subject's sternumjust below the nipple level. Within this radius G, the sensor 20collects both respiratory and cardiac data for simultaneouslydetermining both respiratory and cardiac rate and rhythm, along withcardiac stroke volume and respiratory tidal volume. The sensor 20 may beattached to the subject using a belt, band or strap 80 that wraps aroundthe subject's chest and holds the sensor 20 in place. The strap 80 restsover the recess 24 in the top 23 of the casing 22. The strap 80 includesa rubber protrusion 81 which conforms to the shape of the recess 24 inthe top 24 of the sensor casing 22 and serves to hold the sensor 20 inplace at the desired position. As shown, the sensor 20 may be movedlinearly along the strap 80 in either direction to redirect the UWBsignal to a particular target area, to improve signal response from aparticular target area or to collect data from other desired portions ofthe chest cavity. Alternatively, a caregiver may hold the sensor 20adjacent the subject's chest in the desired location to collectrespiratory and cardiac information, or lay the sensor 20 in differentlocations on the subject's chest when the subject is in a recumbentposition, without the use of the strap 80.

5. Waist-Centric Single Sensor for Monitoring Respiration Rate andRhythm

FIG. 11 is an illustration of an alternative application and version ofthe apparatus 10 comprising a single sensor 20 wherein the sensor 20 ispositioned at the subject's waist to monitor diaphragmatic motion. Theapparatus 10 consists of a single sensor 20 having a transmitter 30,receiver 40 and respiratory sensor module 50. The sensor 20 is engagedwith a waistband 82 and worn about the subject's waist. The waistband 82includes a rubber protrusion 81 which mates with the recess 24 in thetop 23 of the sensor casing 22 to hold the sensor 20 in place. In thisconfiguration, the apparatus 10 primarily measures and monitors thecyclical motion of the subject's diaphragm muscle D to determinerespiratory rate and rhythm, along with other derivative respiratorymetrics. The sensor 20 may be placed in the middle of a subject'sabdomen, or, located anywhere about the subject's waist including thesubject's side, to measure movement of the diaphragm D during arespiratory cycle.

This version and configuration of the apparatus 10 is well-suited to usein athletic activities where placement on the chest could beconstraining. Although the focus would be directed to trackingrespiratory performance, this version will also collect cardiacinformation from elements of the anatomy in the diaphragm area whichreflect cardiac performance, for example, via blood vessel pulsing.

6. Wireless Sensor Array in Article of Clothing

FIG. 12 is an illustration of an alternative wireless embodiment 100 ofthe present invention, comprising of one or more wireless sensors 120.The embodiment 100 comprises a vest 110 worn by a subject. The vest 110is designed to receive and hold one or more wireless sensors 120deployed at strategic locations about a subject's upper body and waistto monitor particular portions of the subject's upper body and abdomen.Each sensor 120 includes a transmitter 130 and receiver 140. A centralcommand and control hub 150 is deployed within the vest 110 to receivedata from each of the sensors 120 and to transmit information to otherentities. Each sensor 120 includes an external communications antenna142 which serves to communicate data collected to the central hub 150and to receive control signals from the central hub 150. The central hub150 includes an antenna 152 for receiving data from each sensor 120, forcommunicating data to external sources and for receiving control signalsfrom external sources, which control signals may then be communicated toeach sensor 120.

Thus deployed, the multiple wireless sensors 120 are able tosimultaneously measure mechanical movement of various anatomicalelements that are indicative of respiratory functionality. By trackingone or more respiratory-induced movements simultaneously, the embodiment100 will qualitatively and quantitatively characterize breathingpatterns and exertion by detecting movement of anatomical elementsassociated with quiet, deep and other forms of respiration.Additionally, as shown, the sensors 120 may be deployed in proximity toeach individual lobe of each lung to provide direct and independentmonitoring of each lobe.

As shown in FIG. 12, the lung complex includes left and right lungs LL,RL which are further subdivided into upper, middle and lower lobes. Eachlobe has a different shape having independent volumetric expansion andcontraction behavior along with different perfusion and dielectricproperties. The left lung LL comprises an upper lobe LUL and lower lobeLLL; the right lung comprises an upper lobe RUL, middle lobe RML andlower lobe RLL. Strategic positioning of sensors 120 above eachindividual lobe provides a novel approach for monitoring respiratoryperformance by directly tracking the performance of each lobe of eachlung, rather arbitrarily monitoring thoracic expansion and contractionwhich delivers only a measure of overall respiratory rate and rhythmwithout disclosing any information concerning the functionality of eachindividual lobe of each lung. The present invention is unique in itsability to individually, simultaneously and noninvasively monitor theperformance of each lobe of each lung to allow noninvasive monitoring ofphysiologic behavior which may more quickly point out certainrespiratory concerns. For example, since certain types of breathingcreate a ventilation/perfusion mismatch, simply monitoring overallrespiratory rate and rhythm via thoracic expansion and contraction wouldfail to provide information concerning performance of individual lobesduring a respiratory cycle. The present invention supports a highlygranular and faithful assessment of the performance of each individuallobe of each lung during a respiratory cycle, allowing a diagnosticianto scrutinize differing behaviors between each lobe.

Now, in greater detail and referring to FIG. 12, an embodiment 100 ofthe present invention is shown comprising a wearable garment 110 such asa vest where a plurality of sensors 120 are deployed throughout thegarment 110 to support specific targeted monitoring of differentportions of the thoracic/abdominal volume. In a first version, to obtainincreased volumetric accuracy, five sensors 120L are incorporated withinthe garment on the individual's front at positions above each lobe ofboth lungs. In a second version, an additional sixth sensor 120C ispositioned approximately directly above the middle of the sternum tosupport simultaneous acquisition of cardiac signals including rate,rhythm and stroke volume, along with respiratory rate and rhythm. In analternative version, five additional sensors 120S are deployed in sidelocations of the vest 110 to replace or complement measurements at eachlobe for sensors 120L. In addition, although not shown here, one or moreof the six sensors 120L, 120C may be repositioned in the vest to beplaced adjacent an individual's back. Further, in an additional versionnot shown here, sensors 120 may be placed in the garment 110 on both thefront and back to maximize the data gathered to enhance accuracy ofmeasurements by relying to a greater degree on increased granularity ofdata acquisition in support of a more accurate shape model. Finally, asdesired by the diagnostician, the embodiment 100 can incorporateadditional sensors 120 to further increase the granularity ofmeasurements and provide greater resolution to the respiratory model.

The sensors 120 distributed about the garment 110 communicate back to arespiratory hub module 150 via a wireless connection. The hub module 150is preferably incorporated within the garment 110 and also includes acommunications module to allow wireless communication of the collecteddata from the sensors 120 to other locations, such as a remote doctor'soffice, a local nurse's/caregiver's station/computer, or, the computerof some other concerned individual, such as a family member. Forexample, in facilities caring for the elderly, an elderly person wouldwear the monitoring garment 110 and the hub 150 could communicatelocally to an Internet connection to deliver the signal informationacross the Internet to a doctor monitoring the elderly person's healthsigns. In another version, not illustrated here, the sensors 120including the antennae 130, 140 and associated miniature signalprocessing and storage units are implanted under an individual's skin.The data is communicated from the implanted sensor to an external CPU ina wireless manner. The external CPU may then use the associatedcommunications module to communicate the data to other entities.

The wireless sensors 120 are deployed to target or interrogate variousportions or regions of the upper thorax associated with respiratoryfunctionality. For example, wireless sensor 120C is located in thecenter of the chest adjacent a midpoint of the sternum to capture bothcardiac and respiratory motion. Five additional sensors 120L are locatedadjacent specific portions of a subject's lungs L to monitor theperformance and functionality of each lobe of each lung L independentlyof the other lobes. Additional wireless sensors 120S are deployed alongthe subject's side in proximity to each lobe of each lung to provide analternative measure of motion and functionality for each lobe. Inaddition to the wireless sensors 120 deployed about the chest of thesubject, the present multi-sensor embodiment 100 also includes awireless sensor 120W preferably located at the middle of a subject'swaist, held by a belt or waistband 112 to target movement of thediaphragm D. Sensor 120W monitors and tracks the motion of thediaphragmatic muscles D to provide an additional measure of respiratoryfunctionality. Each wireless sensor 120 includes a separate datacommunication antenna 142 which delivers collected data to a wirelesssensor hub module 150 located within a pocket or other holder of thevest 110. The data communication antenna 142 can support datatransmission to the hub module 150 using one of several knowntelecommunication protocols, including Bluetooth and UWB. Although shownhere as having wireless connectivity, the sensors 120 could alsoalternatively be connected via wired links which run through the articleof clothing to the sensor hub module 150.

Although shown as associated with a vest 110, the wireless sensors 120may be deployed in other types of clothing articles, may be deployed inpockets of a clothing article, may be attached to a Velcro patch, may besewn and integrated in a piece of clothing, and, may be deployed inconjunction with other devices such as a defibrillator. The wirelesssensors 120, for example, could be integrated in a bullet-proof vest,personal armor, a jacket, a protective piece of clothing used by aworker in an industrial setting, a wetsuit, a fully enclosed suit usedin hazardous response or incident response, and further, within a spacesuit used by astronauts in space exploration. The apparatus 100 is tunedand calibrated to accommodate any attenuation or change in signaltransmissivity associated with different types of materials used in thearticle worn by the subject housing the wireless sensors 120. Thusdeployed, the wireless sensors 120 can be positioned to independentlyand individually monitor functionality of each lobe of each lung L andthe heart H. For example, wireless sensor 120C is positioned to monitorthe heart H and lungs L simultaneously. Multiple sensors 120L and 120Sare positioned to independently measure the functionality of each of thevarious lobes of the lungs including the upper lobe of the right lungRUL, the middle lobe of the right lung RML, and the lower lobe of theright lung RLL. Further, additional wireless sensors 120S and 120L arepositioned to measure functionality of the upper lobe of the left lungLUL and the lower lobe of the left lung LLL. Although not shown in FIG.12, the wireless sensors 120 deployed in the front of the vest 110 couldlikewise be deployed in similar positions on a backside of the vest 110.Additionally, the wireless sensors 120 could be deployed in allpositions simultaneously including front, side and back, providinghigher density data collection and the opportunity to aggregate andcompare data from multiple wireless sensors 120 simultaneously.

7. Wired Sensor Array

FIGS. 13-15 are illustrations of an alternative version of amulti-sensor embodiment 200 comprising multiple sensors 220 adhered tothe surface of a subject's skin. Each sensor 220 communicates via wiredlinks 210 to a central hub 250. FIG. 13 is a front view of a subjectillustrating the deployment of a plurality of wired sensors 220 on asubject's front. FIG. 14 is a back view of the subject illustrating thedeployment of a plurality of wired sensors 220 on a subject's back. FIG.15 is a top view of the subject illustrating the deployment of multiplesensors 220 about the front, back and side of the subject's upper torso.The deployment of a plurality of sensors 220 about the upper torso of asubject allows data to be collected from a plurality of strategiclocations. This data can then be aggregated to create a highly resoluteassessment of respiratory performance, and, to determine the location ofany problematic areas or anatomical elements, such as in determining theonset of congestive heart failure as determined by measurement ofchanges in dielectric values in the various lobes of the lungs.

Referring to FIG. 13, multiple sensors 220 are placed strategicallyabout a subject's thorax and abdomen and positioned to capture movementof key anatomical elements involved in respiration, including both quietand deep breathing. The sensors 220 communicate collected reflectedsignals S′ and associated data via wired links 210 to a central datacollection, processing and distribution hub 250. Multiple sensors 220Land 220S are positioned to collect data from each lobe of each lung,including the right lung upper lobe RUL, the right lung middle lobe RML,the right lung lower lobe RLL, the left lung upper lobe LUL and the leftlung lower lobe LLL. Sensor 220C is positioned in the middle of thesternum to simultaneously collect cardiac and respiratory informationfrom a location where the transmitted signals S capture both respiratoryand cardiac-related motion. Sensor 220W is positioned to measure motionof the diaphragm D to primarily collect respiratory information, but mayalso be used to pickup cardiac rate and rhythm via motion associatedwith each pulse. By measuring the motion of these elements, or lackthereof, the level of effort being expended by an individual may bedetermined.

Following are illustrative examples of specific anatomical motion to bemonitored and tracked by the sensors 220. This motion is correlated andaggregated to develop the various measures and metrics of respiratoryperformance relative to various disease states. The data collected maybe aggregated and disaggregated as necessary to support a plethora ofdifferent analyses relative to the condition being evaluated. Forexample, during deep breathing, one would expect the manubrium sterni tomove 30 mm in an upward direction and 14 mm in a forward directionduring inspiration. Additionally, the width of the subcostal angle, at alevel of 30 mm below the articulation between the body of the sternumand the xiphoid process, is increased by 26 mm. Further, the umbilicusis retracted and drawn upward for a distance of 13 mm. By measuringthese and other movements induced by respiration, the multiple wiredsensor embodiment 200 of the present invention obtains mechanical motiondata that is processed via one or more algorithms in software orhardware to produce qualitative and quantitative respiratory metrics.

The data from each sensor 220 is delivered via hard-wired data links 210to a hub 250, which is shown in this version as being worn on thesubject's hip. As shown in FIG. 13, the wired sensors 220 are adhered tothe subject's chest, back and waist in strategic locations comparable tothe placement of wireless sensors 120 in the vest 110 illustrated inFIG. 12. Thus configured, the wired sensors 220 are able to interrogateportions of the subject's lungs or measure different portions of thesubject's muscular and other anatomical elements that exhibitrespiration-induced motion. As shown in FIG. 15, where wired sensors 220are positioned at opposing locations of opposing sides of the subject'sbody, the embodiment 200 is able to collect and compare data fromdifferent portions of the lungs and use comparative analyticaltechniques to confirm that all sensors 220 are tracking properly andcollecting functional and other data reflective of counterpart sensors220 on the subject's torso which should be measuring and obtainingsimilar empirical data.

Although the embodiment 100 having wireless sensors 120 and theembodiment 200 having wired sensors 220 are shown as being separateembodiments, a third derivative embodiment would comprise a hybridconfiguration including both wireless sensors 120 and wired sensors 220.The integration of both the wireless embodiment 100 and wired embodiment200 would provide an additional deployment configuration to supportspecial requirements in certain instances. For example, wired sensors220 could receive power from a larger battery pack worn by a user tosupport a greater duty cycle to collect more frequent data whilewireless sensors 120 could be deployed at locations where wired links210 might encumber movement. This combination would provide greaterflexibility in determining where to collect data, how long to collectdata, and, how much data to collect.

8. Linear Multiple Sensor Interrogation

In an alternative embodiment of the apparatus 10, as illustrated in thecross-sectional views of FIG. 16A and FIG. 16B, several sensors 20 aretargeted toward specific portions of a subject's chest cavity to createmultiple interrogation volumes 60 to capture and encompass multipledefined respiratory chambers 70, along with the static and dynamicproperties of each respiratory chamber 70. Each respiratory chamber 70serves as an independent and autonomous model having independentproperties and behavior for each specific portion of the respiratorychamber 70 encompassed by the interrogation volume 60. Additionally,each of the individual respiratory chambers 70 may be aggregated andcoupled to reflect the excursion for a more complex respiratory chamberconfiguration, providing a highly granular yet more accurate assessmentof instantaneous respiratory chamber volume and respiratory parameters.As shown in FIG. 16A, the sensors 20 are preferably deployed in a lineararrangement to create a common plane of interrogation within the chestcavity and to support synchronization and comparison of data collectedfrom the proscribed portions of the subject's chest.

FIG. 16A and FIG. 16B are illustrations of a version 10 of the presentinvention with sensors 20 deployed in a circumferential fashion across asubject's chest. FIG. 16A is a cross-section view of an individual'schest cavity with multiple sensors 20 of the apparatus 10 deployed aboutthe subject's chest. FIG. 16B is a magnification of that sensor 20 andinterrogation volume 60 circumscribed by the line 16B. This magnifiedview illustrates the operation of a sensor 20 interrogating a targetarea or volume 60 of the chest cavity encompassing aspects of theskeletal structure, the lungs and the heart, along with the pleuralspaces and the myriad tissue interfaces comprising the particular targetarea.

Each sensor 20 includes a transmitter 30 and receiver 40 to transmit,receive and collect reflected data associated with mechanical aspects ofrespiration. The reflected signals S′ are received and processed by arespiratory sensor module 50 capable of resolving a change in a spatialconfiguration of the subject's lungs or movement of an internal tissue,such as ribs, diaphragm, chest wall, lung tissue surfaces, and othertissue interfaces which correlate with respiratory-induced motion,thereby determining respiratory rate and rhythm. Each sensor 20interrogates a portion of the chest cavity to track motion anddielectric state within a target interrogation volume 60. Each targetinterrogation volume 60 encompasses a defined respiratory chamber 70comprising a portion of the overall respiratory model according to theinvention. One or more target regions or volumes of the right lung RL,left lung LL, or associated tissues whose movement is influenced bymotion during the respiratory cycle may be continually interrogated.Each target interrogation volume 60 may be independently analyzed as asingle respiratory chamber 70 or aggregated with measurements from otherinterrogation volumes 60 to comprise an overall respiratory chamber 70comprised of one or more respiratory chambers 70. The respiratorychamber 70 comprises a volumetric portion of the lungs, which ismonitored by one or more sensors 20. Each respiratory chamber 70 has aprescribed geometry and associated volume driven by sensor 20 placement.Each sensor 20 tracks an interrogation volume 60 which encompasses andcaptures all or a portion of a complete respiratory chamber 70 and eachsensor 20 contributes its information to an overall assessment ofrespiratory chamber dynamics. The aggregated measurements from each ofthe interrogation volumes 60 which form the desired respiratory chamber70 are extracted for use in calculating the various respiratoryparameters and metrics associated with the selected respiratory chamberconfiguration.

Now, in greater detail, with continued reference to FIGS. 16A and 16B,in practice, each sensor 20 transmits a series of extremely shortduration electromagnetic pulses S into the human body toward areas ofinterest in an interrogation volume 60. As the energy enters the bodyand encounters a boundary between different biological substances suchas skin-fat, muscle-blood, tissue-air, or bone-fluid, small amounts ofthe incident energy are reflected back towards the sensor 20 where thereflected signals S′ are captured and pre-processed. Each combination oftissues exhibits its own factor of reflectivity.

Each sensor 20 captures raw reflections using a high speed sample andhold circuit where the desired capture time for the sampler is set toequal the round trip time of flight of a transmitted signal S from thesensor 20 to a target or range of interest T and back to the sensor 20.Sampled reflections S′ from a given depth or range of depths areintegrated to minimize high frequency noise that may corrupt the desireddata related to tracking instantaneous respiratory volume, rate andrhythm. The integrated signal is amplified and passed through a low-passfilter to prevent signal aliasing prior to digitization. After apredetermined number of reflections S′ for a first range of interest arecollected and integrated, the sensor sample timing is changed, allowingcapture of reflections from the next range of interest. This process isrepeated until reflections S′ from the entire range of interest, such asacross a portion of the chest cavity, i.e., the interrogation volume 60,are collected. The process is then continually repeated to deliver anupdated instantaneous measure of respiratory volumetric changes, and,associated respiratory rate, rhythm and other derivative parameters,associated with one or more interrogation volumes 60 and a prescribedrespiratory chamber configuration.

For dynamic monitoring of physiological structures such as the lungs L,the physical location of the boundaries within the target range ofinterest will move with respect to the generally fixed position of thesensor 20 and its antennae 30, 40, producing a complex series oftime-varying reflections S′. The time-varying reflections S′ arecontinually processed by the sensor 20 to extract both mechanicalinformation and electrical information associated with the activity ofthe lungs.

In FIG. 16B the sensor 20 generates an interrogation volume 60encompassing a respiratory chamber 70. The respiratory chamber 70includes portions of the subject's heart and left lung LL. By measuringthe excursion and motion of the various tissue interfaces within therespiratory chamber 70, the apparatus 10 is able to assess both cardiacand pulmonary performance.

9. Multiple Sensor Lobe-Centric Configuration for Obstruction Detection

FIG. 17 provides an illustration of a further application and embodimentof the apparatus 10 of the present invention building on the featuresand functionality of earlier described embodiments, particularly theembodiment illustrated in FIGS. 2 and 3. In this version, the inventionis able to determine the location of obstructions within a subject'sbronchii based on the measured behavior of individual lobes of eachlung. The apparatus 10 comprises five or more sensors 20 positioned atstrategic locations on a subject's chest to monitor and track theindividual lobes of each lung. The sensors 20 can be deployed in eithera wired or wireless configuration. FIG. 17 is a cut-away view of asubject's chest, revealing both the left lung LL and right lung RL. Eachlung LL, RL is further delineated into its individual lobes. The rightlung RL comprises a right upper lobe RUL, a right middle lobe RML, and aright lower lobe RLL; the left lung LL comprises a left upper lobe LULand a left lower lobe LLL. In practice, individual sensors 20 arepositioned on a subject's chest so as to monitor motion and state ofeach of the five lobes independently. With sensors 20 strategicallypositioned to interrogate a volume 60 and respiratory chamber 70 in eachindividual lobe, the apparatus 10 is able to deliver informationconcerning the respiratory functionality of each individual lobe.Consequently, the apparatus 10 may be used to identify whether a subjecthas any obstructions in any of the bronchi.

For example, in operation, where there exists a blockage B1 in the leftlung LL, a sensor 20 positioned adjacent the left lower lobe LLL woulddetect a decrease or delay in inflation of the left lower lobe LLL ascompared to inflation in the left upper lobe LUL as measured by aseparate sensor 20. Consequently, based on the comparison, a physicianwould be able to determine that some form of obstruction or otherrestriction existed in the area of blockage B1. Thus, a condition may beisolated to a more specific location. Still further, in the situationwhere a blockage B2 in the brachia of the bronchia supplying air to theright upper lobe RUL is present, the sensor 20 positioned to monitor theright upper lobe RUL would measure less or delayed inflation as comparedto a normal, unobstructed circumstance or as compared to the measuredbehavior of another lobe, such as the right middle lobe RML. Likewise,in the circumstance where an obstruction B3 occurs, sensors 20positioned to monitor the right middle lobe RML and the right lower lobeRLL would detect less or delayed inflation as compared to a normal statewithout an obstruction, or, as compared to relative inflation of theright upper lobe RUL. Thus, the apparatus 10 of the present inventionwould be able to provide indications of obstruction or restriction inthe bronchii or branches thereof, without having to initially resort tothe use or more invasive procedures and instruments. Once the generallocation of an obstruction or restriction has been identified using theapparatus 10, a physician would then be able to minimize the exploratoryrequirements using more invasive instruments and techniques. Instead,for example, having determined that a blockage exists at any of thesites B1, B2, or B3, the physician could focus his investigation onindicated locations. In addition to obstruction detection, the presentembodiment would also support the detection of a tension pneumothorax orhemopneumothorax by identifying reduced inflation in portions each lobeor each lung.

10. Multiple Sensor Lobe-Centric Configuration for Congestion Detection

FIG. 18 is an illustration of a further embodiment of the apparatus 10invention directed toward monitoring pulmonary congestion indicative ofcardiac performance deterioration or other disease states. Congestiveheart failure is a serious physiological condition that is associatedwith changes in respiratory performance. FIG. 18 provides an exemplaryillustration of an individual where the right lung RL is clear andwithout congestion, while the left lung LL is shown as having a buildupof fluid in its lower regions, suggesting the onset of congestive heartfailure, the presence of other disease states, or, the presence of apneumothorax, hemopneumothorax or other actual damage to the lungs whichhas resulted in a buildup of fluids either within the lung tissue oroutside the lung in the pleural space. Congestion can occur even in ahealthy person during bouts of pneumonia or other ailments whichcompromise the respiratory system.

In one embodiment, as illustrated in FIG. 18, congestion in lungs may bemonitored by one or more sensors 20. Referring as well to FIGS. 16A and16B, in a congestive heart failure monitoring mode, the apparatus 10transmits a series of pulses at a target respiratory chamber 70comprised of one or more interrogation volumes 60. The apparatus 10comprises one or more sensors 20 having a transmitting antennae 30 andreceiving antennae 40. The transmitting antenna 30 of each sensor 20directs electromagnetic energy in the form of an ultra-widebandradiofrequency signal S toward a target area T circumscribing a targetrespiratory chamber 70. A portion of the transmitted energy is reflectedback to the receiving antenna 40, in part, due to the large differencein dielectric value between the air and liquid in the lungs RL, LL,along with dielectric differences in other tissues in the target area Tof interest.

The apparatus 10 incorporates an advanced algorithm used in conjunctionwith one or more algorithms of the respiratory sensor module 50 forcapturing dielectric information to support capture and processing ofadditional data to assist in determination of changes in dielectricmeasurements during a respiratory cycle. As additional fluid builds upin the lungs RL, LL, the various sensors 20 will monitor the dielectricvalue in the various portions of the lungs RL, LL. For example, thesensors 20 will continually measure the dielectric value in the rightupper lobe RUL, the right middle lobe RML, the right lower lobe RLL, theleft upper lobe LUL, and, the left lower lobe LLL.

In FIG. 18, portions of both the left lower lobe LLL and the left upperlobe LUL are shown as having a buildup in fluid content as compared tothe lobes of the right lung RL and as compared to the normal state ofthe left lung LL. As the sensors 20 measure the change in the dielectricvalues of portions of the lungs RL, LL, the apparatus determines whetherthere is a change associated with a trend toward congestive heartfailure. The methods of the present invention associated with measuringand comparing the changes and trends in dielectric values to assess thepotential or actual onset of congestive heart failure are describedlater in this document.

11. Variable Adaptive and Customizable Lung Models

The present invention supports the use of various two-dimensional andthree-dimensional lung models. In particular, the present inventionsupports a novel method for use of lung models wherein each lobe of eachlung can be modeled separately and independently from each of the otherlobes, and then, aggregated or compared with information from monitoringof the other lobes to provide unique analytical, diagnostic andtreatment opportunities. The present invention also supports a novelmethod for modeling multiple portions of each lobe of each lung alongwith other portions of the anatomy which might be relevant to anassessment or diagnosis. With an increase in the number of sensors used,the model for the present invention can provide a highly granular andresolute assessment of respiratory performance. The lungs can be modeledusing a number of different shapes which may affect the accuracy andprecision of the measurements depending on the coarseness of the model.In certain versions, use of a single sensor 20 may be sufficient for theaccuracy desired. Other applications may benefit from having data frommultiple sensors 20 aggregated in a more complex model.

For example, in a first version, and with reference to FIG. 2, each lungis presumed to be in the shape of simplified rectangular box havingdimensions roughly approximating the size of the lungs. In this instancethe excursion from just one sensor 20 may be used to drive the entirerespiratory model. Accuracy of the model will vary depending on the typeof breathing and closeness of this model to actual empirical behavior ofthe lungs of the specific individual.

In a second version, and with reference to FIG. 16A, a more complex lunggeometry and shape may be used in the algorithm of the presentinvention, where data from individual sensors drive individual portionsof a complex model and those individual portions are aggregated asappropriate to determine desired pulmonary metrics. For example, themodel may be comprised of shapes for each lobe of each lung whereindividual sensors 20 measure the excursion of each individual lobe andthen the data is aggregated to produce overall pulmonary metrics. In oneapplication, as described earlier, the apparatus 10 determines thepresence of an obstruction within the lung, such as a penny or a peanut,by observing data from each sensor 20 and isolating the sensor 20 andlobe indicating reduced or abnormal excursion during a respirationcycle. For example, excursion which is reduced during inspiration canindicate that an obstruction is present which is impeding flow into aparticular lobe; reduction of excursion which is delayed duringexpiration can likewise indicate an obstruction or other form ofrestriction, such as the presence of asthma or other disease state whichhas caused an inflammatory condition in the lungs. Likewise, thisinformation could be used to indicate the ingestion or inspiration ofsome type of hazardous material or biologic material known to causeinflammatory or other detrimental conditions in a person's lung complex.

In a third version, a simple rectangular box may be used as the desiredgeometric model to both simplify calculations and to leverage excursiondata from preferably just one sensor. The box is sized so as to moreclosely approximate the actual volumetric behavior of the lungs incorrelation with actual excursion distances measured by the desiredsensors. This version is developed by preferably acquiring empiricalrespiratory performance data from an individual by measuring actualrespiratory performance during respiratory cycles using othermeasurement devices, such as a plethysmograph. Using this empiricaldata, a custom algorithm accurately representing the individual'srespiratory performance is produced and incorporated in the algorithmand method of the invention. This custom algorithm and associatedgeometric model is optimized to support measurements from a minimumnumber of sensors, preferably, just one sensor.

In a fourth version, a very detailed shape may be used for the lungmodel based upon data from other imaging technologies, combined withempirical data, to generate a highly resolved algorithm correlated withhigh granularity to the individual's physiology and number and placementof sensors and, multiple measures of excursion may be applied to themore complex model to develop a more accurate and precise measure ofpulmonary functionality. For example, highly resolute data from X-ray,MRI or other imaging technologies may be used to create a more accuratelung model. Since respiratory performance measurements need notnecessarily rely on a highly resolved model capable of determining exactabsolute values, the present invention is highly functional and usefulusing a coarse model.

So, in a first approach and application, the apparatus and method of thepresent invention calculates instantaneous respiratory volume byapplying the measured excursion distance from a prescribed respiratorychamber 70 of a target interrogation volume 60 to a simplifiedrectangular model and calculating the volume of a simple rectangular boxusing a measured excursion distance between the front and back walls ofthe box at a particular point in time. Subsequently, the apparatus andmethod calculates the change in instantaneous volume as a function oftime, thereby supporting the calculation and assessment of pulmonarytidal volume. As indicated above, the IRV module of the presentinvention is adaptive to include more complex volumetric calculationmodels based upon a more complete physical model of the targetedrespiratory chamber, including a model based on more complex staticimaging, such as from an MRI, X-ray or other imaging device. Empiricaldata may be used and correlated to the signals processed by the IRVmodule to arrive at a highly accurate measure of instantaneous lungvolume and derivate parameters, including tidal volume. Additionally, ina further embodiment, where a more complex model of the lung is used,additional sensors 20 may be deployed at multiple locations along thechest or back in correlation to the model to collect multiple and moreresolute excursion distances for each key section of the complex lungmodel. For example, sensors 20 could be placed over the upper, middleand lower lobes of both lungs and excursion distances collected for alllobes, each having their own specific geometric shape and behavior. Bycalculating the excursion distance for each lobe of the lung, theinvention is also able to determine if there is a potential physicalobstruction in one of the branches of the lung, such as a peanut orpenny, by comparing the changes in each lobe to each of the other lobesduring a respiratory cycle.

During monitoring, once the apparatus 10 has calculated instantaneouslung volume, the change in instantaneous lung volume over time is alsocalculated. Then, the apparatus 10 is able to calculate all otherderivative pulmonary functional parameters.

For example, tidal volume is calculated by taking the difference betweenthe maximum and minimum respiratory chamber volume during eachrespiratory cycle. Respiratory output is calculated by multiplying thetidal volume by the respiratory rate. Respiratory rate and rhythm areacquired by measuring the maximum and minimum excursion over time aswell. The present invention is able to measure and determine thesevarious pulmonary and respiratory metrics to support monitoring of anindividual's respiratory health and performance. Once all desiredrespiratory/pulmonary parameters have been developed by the apparatus10, the results may be presented to various users in a manner mostappropriate for the individual's or user's needs.

12. Concurrent Cardiac and Pulmonary Assessment

In an alternative embodiment, the present invention demonstrates a novelapparatus and method using ultra-wideband radar to detect conditionswithin the thoracic and abdominal areas that will lead to adetermination of changes in lung volume. In particular, the apparatus 10of the present invention supports the instantaneous and continuousnoninvasive measurement of changes in lung volume, while also measuringparameters including respiratory rate and rhythm. In addition torespiratory rate and rhythm, the apparatus and method of the presentinvention provides an instantaneous assessment of tidal volume and otheradvanced respiratory parameters. Consequently, the apparatus provides aunique capability to continuously and instantaneously monitor and trackpulmonary functionality to provide critical information on the health ofboth the pulmonary and cardiovascular system.

Additionally, the apparatus and method of the present inventionsimultaneously extracts medical and physiological data from subjectsconcerning both cardiac and pulmonary performance and functionality toproduce respiratory knowledge. The apparatus measures cardiopulmonaryfunction without direct skin contact. The apparatus preferably comprisesa miniature UWB radar transceiver connected to a data processing devicehosting unique software and associated signal processing components. Theapparatus, in combination with proprietary algorithms included in thesoftware and hardware components, produces a novel output that allowsone to non-invasively detect and track heart and lung motion, along withinstantaneous volumetric information and dielectric information. Theapparatus collects cardiopulmonary rate and rhythm information for usein patient monitoring prior to an abnormal event, during an event, and,to evaluate treatment such as resuscitation efforts.

The apparatus utilizes electromagnetic energy to interrogate the bodyand extract physiological data. The methods associated with theapparatus use Finite Difference Time Domain (FDTD) analysis techniquesto model the electromagnetic interaction between complex 3-dimensionalphysical systems such as the human body and the radar antennas of theapparatus used to transmit and receive electromagnetic energy.

The present invention incorporates novel geometrical models andfunctional algorithms which account for various nonlinearities andprovide a correlation between lung surface area and volume. In a furtherembodiment of the present invention, the apparatus and method providesan initial three-dimensional empirical measure of the size and shape ofeach lung, which is then used by the microprocessor 56 of therespiratory sensor module 50 and associated software to generate asignificantly more precise and accurate measure of the actual volumetricchanges of a specific individual's lungs during a respiratory cycle.

As illustrated in FIG. 12, to provide more specific informationconcerning changes in lung volume, sensors 120 may be placedstrategically to capture changes in portions of the lungs, including theupper, middle and lower lobes. Integration and comparison of the changesin volume in individual lobes will provide a more accurate assessment ofoverall pulmonary functionality, and, allow additional diagnosticassessments to be performed by measuring and comparing changes betweenthe lobes where differential lobe behavior is know to predict certainpulmonary functionality that is relevant to diagnosing particularconditions. For example, as illustrated in FIG. 17, measurement ofminimal excursion in one lobe below an expected value, juxtaposedagainst measurement of normal excursion in other lobes, can beindicative of a physical obstruction in a portion of a lung or someother indicated condition, such as early diagnosis of lung congestionindicative of potential heart failure.

The present invention provides an assessment of changes in respiratorychamber volume to provide useful diagnostic information and respiratoryknowledge, irrespective of the specific size and shape of a subject'slungs. However, in a further embodiment of the present invention, thesoftware allows the specific lung shape and size to be changed toaccount for expected differences as a result of age, muscularity, orother factors to produce more accurate absolute assessments of pulmonaryfunctionality.

In a still further embodiment of the present invention, the software ofthe apparatus 10 is able to ingest data from other existing staticimaging systems such as MRI, CT, or ultrasound for use in determiningthe shape and size of a particular individual's lungs and associatedrespiratory chamber dimensions to increase the accuracy of respiratorymeasurements. Two-dimensional and three-dimensional information obtainedfrom other imaging systems may be ingested and adapted to thespecialized model and correlated to the apparatus 10.

In an alternative embodiment, where it is desirable to collectinformation concerning both cardiac and pulmonary functionality, theapparatus 10 and method of the present invention include guidelines forantenna placement. FIG. 10 illustrates an embodiment comprising at leastone sensor 20 positioned adjacent a subject's sternum to capture bothcardiac and pulmonary information. Sensor 20 placement can be animportant parameter and can affect the strength of received reflectionsS′. To support simultaneous collection of both cardiac and pulmonaryinformation, including stroke volume and tidal volume, respectively, asensor 20 is placed adjacent the subject's sternum within a prescribedradius G. Generally, it is preferable that the sensor 20 be placedwithin a radius G of 3 centimeters from the midpoint of the sternum at apoint just below a line intersecting the subject's nipples. A sensor 20may be placed at other locations, and need not be placed in closeproximity to the center of the sternum, to capture cardiac and pulmonaryrhythm and rate information. For example, as shown in FIG. 12, in oneembodiment of the present invention, a sensor may be placed under theleft arm or on one's back and still obtain data to track and monitorboth cardiac and respiratory rate and rhythm.

Referring to FIG. 10, in a preferred embodiment of the present inventionwhere it also desirous to collect cardiac data including stroke volume,the sensor 20 is placed in close proximity to the subject's sternumrather than on the side chest wall. This placement provides a consistentcalibration approach to maximize the resolution and accuracy of theinterrogation process. Additional attenuation of the cardiac signal willbe experienced in an underarm case due to the increased distance of thesensor 20 from the heart. However, in the present invention, as shown inFIGS. 2, 3, 12 and 13, one or more sensors 20 may be placed anywhereabout the thorax and abdominal regions, including the lower back, tocollect data indicative of pulmonary function, including respiratoryrate and rhythm. Many of these same locations will also deliver cardiacrate and rhythm information. Although the present invention contemplatesthat the transmit and receive antennae 30, 40 will be integrated withother sensor 20 elements as one unit, the antennae 30, 40 may bedeployed separately from the other sensor 20 elements.

Referring to FIG. 10, in greater detail, when both cardiac and pulmonarydata are desired, including cardiac stroke volume and respiratory tidalvolume, a preferred position for the sensor 20 and its antennae 30, 40is on the subject's chest within a radius G of approximately 3centimeters from the center of the subject's sternum.

As illustrated in FIGS. 12-15, additional embodiments of the presentinvention include multi-sensor arrays deployed in close proximity to thetargeted areas, such as the upper, middle, and lower lobes of the lungswith both anterior (adjacent the chest) and posterior (adjacent theback) placement, thereby delivering additional data that can beintegrated via the model to provide a more accurate measure ofinstantaneous lung volume.

13. Sensor Targeting Functionality

In a still further embodiment of the present invention, the apparatus 10includes a targeting element that allows the primary signal from eachsensor 20 to be directed to a key focal point within the respiratorychamber 70 to maintain consistent and accurate measurements. Thisfeature considers adjustments to each model required to accommodate thefact that the lungs may change position and orientation with respect tothe antennas 30, 40 during the respiratory cycle. The apparatus 10automatically and continually adjusts the direction of the transmittedsignal using mechanical or electrical means to maintain a consistentview of the focal target area T of the lungs or respiratory chamber 70,and, makes appropriate adjustments to the perceived volumetric changesby integrating the dynamic behavior of the lungs during the respiratorycycle. This targeting element also assists in maintaining accuratemeasurements when motion may be induced by the subject.

14. Adaptive Modeling and Simulation Methods

In another embodiment, the present invention provides adaptiverespiratory modeling and simulations methods. These methods includedevelopment of an FDTD simulation protocol for tracking pulmonaryfunctionality comprising the steps of:

1) creating a 3-dimensional model of antenna structures used in theapparatus (FIGS. 19 and 20);

2) creating a 3-dimensional model of the lungs and surrounding thoracicand abdominal region that is representative of the human anatomicalstructure with associated complex electrical properties for the varioustissue types (FIGS. 23 and 26);

3) creating a simulation of respiratory chamber functionality, includingstarting from a respiratory chamber volume corresponding to maximuminflation, stimulating the system model using a single cycle Gaussianpulse with zero mean as the excitation source; then repeating thesimulations, decreasing the respiratory chamber volume in incrementalsteps until minimum respiratory chamber volume is reached;

4) applying a novel software and hardware signal processing system toanalyze the resultant data and determine algorithmic adjustments toaccurately detect changes in respiratory chamber volume, including,comparing received reflections across a range of respiratory chambervolumes to quantify differences observed, and, correlation with rangesof the UWB receiver.

Referring to FIG. 4 and FIGS. 16A and 16B, the present inventionincludes a process for refining and tuning its own algorithmic processesto support accurate, calibrated operation of the apparatus 10. First,finite difference time domain (FDTD) models of the lungs and chest aredeveloped and applied based on both anatomic and complex dielectricdata. The models provide a variety of sizes, shapes, granularities andaggregate configurations to deliver a thorough representation ofexpected patient and subject physiologies and encompass the expectedstandard anatomical variation in the population. The present inventionalso provides for the use of models specific to a particular subject,wherein that model may be derived from other imaging technologies, suchas magnetic resonance imaging, X-ray, ultrasound, infrared or othermethods for determining model configuration and geometry.

The volumetric model associated with a defined respiratory chamber 70 ofthe present invention is designed and configured to provide an accurateassessment of respiratory function. In one version, a single volumetricmodel is used to provide an assessment of respiratory function. Inanother version, one or more smaller volumetric models are developedwherein each model is associated with a specific target interrogationvolume 60. Each target interrogation volume will encompass a definedrespiratory chamber 70 which describes the volumetric model associatedwith the analytical process of the present invention for that specificinterrogation volume 60. Each of the smaller volumetric models and theirrespective respiratory chambers 70 may then be aggregated to create anintegrated volumetric model supported a larger and more complexaggregate respiratory chamber 70. Each volumetric model is comprised ofa volumetric voxel mesh composed of a set of small cubic cells. Eachcubic cell is defined by both its size and several complex electricalproperties associate with the cell. Each volumetric model is alsodefined by a minimum mesh size which is based on the shortestoperational wavelength for the ultra-wideband signals S generated by theapparatus 10. The minimum mesh size used in each volumetric model isdetermined according to the relationship provided in Equation 1, below:

$\begin{matrix}{{{MeshSize}_{minimum} = \frac{\lambda_{minimum}}{20\sqrt{ɛ\; r}}};{\lambda_{minimum} = \frac{c}{{Frequency}_{maximum}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Where:

-   -   ∈r is the relative dielectric constant of the medium through        which the transmitted signal must propagate;    -   c is the speed of light (3×10¹⁰ cm/sec)    -   Frequency_(maximum) is the highest frequency of interest in the        transmitted signal in Hz;    -   λ_(minimum) is the corresponding shortest operational wavelength        for the transmitted ultra-wideband signals measured in        centimeters;    -   20 is the constant used to ensure the mesh size of the model        will be significantly smaller than the minimum wavelength to        ensure the mesh size is an accurate dimension for simulation        purposes.

A three-dimensional structural model of the aggregate respiratorychamber 70, comprised of one or more interrogation volumes 60 and one ormore respiratory chambers 70, corresponds to certain UWB radarrequirements providing a foundation for application of multiplefunctional dynamic models, based on nonlinear mesh deformation usingdynamic models of a respiratory chamber 70 indicative of lungfunctionality. Respiratory models representing total respiratory volumesare integrated as components of the invention.

The respiratory model is tailored to the requirements of the UWB radarof the apparatus 10 to provide sufficient corresponding resolution tosupport respiratory volumetric analysis. Additional variablesinfluencing the signal returns to the apparatus 10 from the respiratorychamber 70 are integrated in the algorithmic elements of the apparatus10. The model includes a process for the interrelation of complexelectrical properties for individual tissues and organs found in thehuman chest. The table below lists various anatomical structure andassociated complex dielectric values used in the FDTD models associatedwith the invention where Epsilon (∈) is the gross permittivity of thetissue and Sigma (σ) is the conductivity of the tissue. The modelfurther includes functionality within the algorithm to adapt the valuesof Epsilon (∈) and Sigma (σ) to the specific frequency spectrum of theUWB signal applied to the tissue encountered in an interrogation volume60. This model may also be adapted to support other frequencies ofelectromagnetic energy applied to the tissue higher than 10 GHz.However, the present description focuses on that frequency windowbetween 3.1 GHz and 10.6 GHz, the spectrum made available by the FCC formedical imaging.

TABLE 1 Complex Dielectric Constants for Various Human StructuresAnatomical Structure Epsilon (ε) Sigma (σ) Bone 12.4 0.2 Fat 4.72 0.05Muscle 60 1.32 Skin 9.9 0.72 Lung 20.5 0.42 Heart 57.48 1.22 Trachea55.9 1.12 Cerebra Spinal 68.1 2.45 Fluid Esophagus 71.1 1.35

The model of the present invention also includes optimized antennaconfigurations responsive to the dielectric values of the anticipatedtissues to provide desired signal transmissivity and reception. Theoptimized antenna configurations ensure that the signals penetratesufficiently in the desired interrogation volume to support calculationof instantaneous respiratory chamber volume. The optimum antenna designsupports application where the antenna is in close contact with a highdielectric material, such as skin or cloth, and, the direction of signalpropagation is into the high dielectric material, and, into thesubject's body. Other embodiments may be based on placement of a sensor20 some distance from a subject's skin, adding another dielectricvariable associated with the air space between the sensor 20 and thesubject's skin. Still further embodiments may be based on placement of asensor 20 outside of an enclosed area to monitor the respiration of aperson or persons within this enclosed area. And, still further, theenclosed area may be a mother's womb and the subject whose respirationis being monitored is the fetus in the mother's womb. Still further, thepresent invention may be adapted to noninvasively monitor both cardiacand respiratory function of the fetus while also monitoring the cardiacand respiratory function of the mother.

Referring to FIG. 4, in one version, the apparatus 10 of the presentinvention comprises a sensor 20 including a transmitting antenna 30 andan identical receiving antenna 40. The transmitting antenna 30 transmitsUWB radar pulses S and the receiving antenna 40 collects reflections S′from the target area T encompassed within the interrogation volume 60and including the associated respiratory chamber 70.

FIG. 19 is an illustration of a version of the invention comprising twoidentical antennas 30, 40 having a Bowtie structure. Additionally, FIG.20 provides an illustration of an alternative embodiment comprising asingle element elliptical (SEE) antenna structure. The antennaconfigurations need not be limited to these two types. A system mayinclude antennas that are not identical but have been sized and tuned toeither more efficiently transmit the signals S, or, to receive thereflected signals S′. These alternative antenna configurations may beingested and adapted for use in the algorithms and methods of thepresent invention.

Operational parameters and specifications of the bowtie antennae and SEEantennae used in versions of the present invention are provided in Table2 below.

TABLE 2 Antenna Parameters Parameter Bowtie Antenna SEE AntennaFrequency Range 1 GHz to 8 GHz 3 GHz to 8 GHz (R_(L) > 10 dB) PhysicalDimensions 60 mm long × 57 mm long × 60 mm wide 33 mm wide Feed CenterEnd

In a preferred embodiment, the present invention uses Bow-tie antennasrather than SEE antennas due to enhanced reflections S′ from the signalstransmitted by the Bow-tie antennas. As illustrated in FIGS. 19 and 20,the bow-tie antenna is physically larger and has improved directivitywhen compared to the elliptical antenna. In addition, the bow-tieantenna uses a start frequency of 1 GHz, while the SEE antenna uses astart frequency of 3 GHz. Lower frequency energy is less readilyabsorbed by the interrogated tissues as compared to higher frequencyenergy. The bow-tie antennae use a spectrum with a larger lowerfrequency component, resulting in stronger received reflections S′.Consequently, in a preferred embodiment of the present invention, theantenna is a bow-tie antenna using a starting frequency of 1 GHz.However, to comply with existing regulatory requirements, such as thecurrently authorized FCC spectrum for UWB medical imaging of between 3.1GHz and 10.6 GHz, another preferred embodiment uses an SEE antennaillustrated in FIG. 20, having a starting frequency of 3.1 GHz.

The present invention also provides for the modification of multipleparameters to support improved calibration. For example, in one version,a transmitted pulse shape is chosen to produce a transmitted frequencyspectrum that complies with the UWB medical frequency band as defined bythe United States Federal Communications Commission (FCC) in Rule &Order 02-48.

The model of the present invention supports the inclusion andmanipulation of the value of variable parameters associated with themodel. Following are descriptions of certain of those parameters alongwith discussion of possible modifications supported by the presentinvention.

FIG. 21 illustrates a simulated transmitted pulse or signal S as viewedin the time domain; FIG. 22 illustrates the corresponding magnitude andphase of the same transmitted pulse S in the frequency domain. Thepresent invention supports the comparison of results from two tests tocalibrate the model based on the yield of quantifiable differences inreceived signals S′. One skilled in the art will recognize that thepower and shape of the transmitted pulse S may be modified to improveprecision and accuracy of measurement. For example, in another version,the power of the transmitted signal S may be increased beyond thatgenerally allowed under the FCC guidelines to improve transmitted signalS penetration depth or to enhance the energy of reflected signals S′.Additionally, one could increase or lower the frequency of thetransmitted signals S to minimize absorption or increase resolution.

FIG. 23 is an illustration of a basic structure of a three-dimensionalanatomical model of the thoracic area associated with the algorithm andmethod of the invention without the inclusion of the lungs or heart butwith a pair of bow-tie antennas positioned over the sternum. In additionto adjustments of mesh size of the model in correlation to signalfrequencies, the resolution of the three-dimensional model may adjustedto provide increased or reduced granularity. This granularity is alsodriven by the selected mesh size. Further, empirical data from otherimaging systems may be ingested within the model to provide a highlyresolute image of a subject's anatomy in the thoracic area. Stillfurther, the apparatus and method of the present invention may be firstcalibrated against other known measurements methods to ensure accuracyand reliability.

FIG. 24 provides an illustrative example of received reflections S′ fromthis model as viewed in the time domain; FIG. 25 provides anillustrative example of the corresponding magnitude and phase of thereceived reflections S′ in the frequency domain. The received signal S′has a large initial component resulting from direct coupling between thetwo antennae 30, 40. In contrast to the symmetrical spectrum of thetransmitted pulse S, the energy of the received spectrum is concentratedin the lower frequencies since human tissue tends to absorb more of theenergy of the higher frequencies. Consequently, in certain circumstanceswhere increased signal penetration is desirable, signal frequencies maybe lowered, or, signal energy increased.

FIG. 26 illustrates a basic structure of the anatomical model of thepresent invention including the heart with a pair of bow-tie antennaspositioned over the sternum. For clarity, the lungs are included in themodel but not shown in FIG. 26. Although shown in this particularembodiment as positioned over the sternum adjacent the heart, to acquiredata representing respiratory rate and rhythm, one or more of theantenna pairs 30, 40 may be placed anywhere around the periphery of thethorax and abdomen since anatomical motion derivative of respiration ispresent throughout this region. This motion can be qualitatively andquantitatively measured by targeting one or more anatomical elementswhich move in correlation with the respiratory cycle, including theribs, internal and external intercostal muscles, abdominal muscles, thediaphragm, lungs, and chest wall. Again, the resolution and accuracy ofthe model can be enhanced by using empirical data from other imagingsystems to more closely match the actual shape of various anatomicalelements within a subject's thorax.

FIG. 27 illustrates simulated received reflections S′ for a case withthe heart and lungs included as viewed in the time domain; FIG. 28illustrates the corresponding magnitude and phase of the frequencyspectrum for the received signal S′.

FIG. 29 provides an illustrative plot of the expected time domaindifference signal calculated by subtracting the data derived from thecase with the heart and lungs from the data derived from the casewithout the heart and lungs. For example, the amplitude of thedifference signal is 0.058 Vp-p as compared to the 2.35 Vp-p amplitudeexhibited by both of the two received signals; a difference of 32.2 dB,establishing an expected minimum sensitivity of the receiver fordetection of gross anatomical details based on the simulations. FIG. 30illustrates the corresponding spectrum of the received signals for thetwo cases.

The present invention further includes a respiratory-specific algorithmaddressing heretofore-unknown behavior where, as the difference inrespiratory chamber volume increases, the length of the differencesignal increases. This relationship is a fundamental aspect of themethod and process of the present invention used in determininginstantaneous respiratory chamber volume (IRV). The delay between atransmitted pulse S and the beginning of a received reflection S′ isdetermined by the finite distance between the antenna plane and thetarget respiratory chamber wall or tissue interface. Differences inrespiratory volume are presented in a quantifiable form by thecomputation of the energy of the recorded signal waveform throughnumerical integration using the following relationship:

W = k ⋅ ∫₀^(T)s²(t) t;

-   -   where k=normalization factor and T=5 nanoseconds, the receiver        time window.

Increases in reflected energy correlate with larger differences inchamber volumes, indicating the ability of the apparatus to measurevariations in the volume of targeted portions of the human lung.

15. Instantaneous Respiratory Volume Modeling Method

The various methods of the present invention further include a methodfor determining instantaneous respiratory volume. This feature is builtupon the versions and embodiments of the present invention capable ofmonitoring respiratory rate and rhythm, and, cardiac rate and rhythm.Fundamentally, the instantaneous respiratory volume (IRV) module of thepresent invention supports the noninvasive acquisition of real-timerespiratory volume without dependence on more complex, invasive methods,such as a plethysmograph, among others.

FIG. 31 is a flow chart of the process and algorithm of the pulmonaryimage quantizer module 300 of the present invention used in determininginstantaneous respiratory volume (IRV) and other pulmonary metrics. FIG.32 is a flow chart of the process and algorithm of the pulmonary motiondetection and metric determination module 400 used in determining IRVand other pulmonary metrics. The results of the image quantizer process300 of FIG. 31 are cross-correlated against the results of the motiondetection process 400 of FIG. 32 in an interactive process to identifyand isolate respiratory chamber wall movement to support determinationof IRV, tidal volume and other respiratory metrics. Consequently, theapparatus and method of the present invention are then able to obtainand calculate pulmonary metrics, such as tidal volume and instantaneousrespiratory volume, which heretofore have required the use andapplication of invasive and cumbersome instrumentation and devices.

References will be made to FIGS. 4 and 5 in this portion of thedescription to support the reader's understanding of various aspects ofthe apparatus and method which support the processes illustrated in FIG.31 and FIG. 32. Now, with reference to FIG. 4 and FIG. 5, forcalculation of instantaneous respiratory volume, the ultra-widebandmedical radar (UWBMR) 54 of each sensor 20 transmits radar signals Stoward the target area T and radar reflections S′ are then firstreceived by the receiving antenna 40 and converted to digital radarreflections.

FIG. 31 is a flowchart describing the binary image quantizer process 300associated with the apparatus and method of the invention. First,digitized data from the ultra-wideband medical radar (UWBMR) 54 iscollected continuously over time 310. The received raw radar reflectiondata S′ from each sensor 20 indicating motion is then aligned on rangesweep scan boundaries 320. The aligned data is then passed through aseries of high pass filters to remove or attenuate both static clutter(reflections from inanimate objects) and lower frequency noise 330. Theresultant motion data is then amplified and quantized to produce aninterim black/white image 370. Next, a speckle filter is applied toremove random speckle noise 380. The removal of the random spectralfrequencies highlights features in the remaining image. The quantizedimage is then stored 390 for subsequent reference in the motiondetection and characterization algorithm and method 400 illustrated inFIG. 32.

The filtering step to attenuate static clutter 330 permits betterdiscrimination of the targeted area associated with each sensor 20 andeasier automatic image segmentation. In addition, after the image for asensor 20 has been filtered, other classical techniques are employed tomore highly discriminate the sensor target area T, including, but notlimited to, contrast improvement, edge enhancement, spatial filtering,noise suppression, image smoothing, and image sharpening.

Once static clutter has been attenuated, for every data sweep, themedian value of the bounded white section for each sensor is calculatedfor every row in the image and the minimum and maximum bin numbers forevery respiratory cycle are calculated 340. The difference in themaximum and minimum bin numbers is multiplied by the spatial resolutionof the system to obtain the change in the radial axes between maximumand minimum lung inflation.

Now, in greater detail, with continued reference to FIG. 31, the digitalradar reflections S′ are stored in memory as received over time 310. Thedigital radar data is then range aligned on sweep boundaries 320. Thealigned data is then passed through a series of high pass filters tominimize low frequency noise and attenuate static clutter, such asreflections from any inanimate objects within the range of interest 330.The resultant data associated with all anatomical motion in the range ofinterest, including respiratory motion and the associated movement ofparts of the anatomy, e.g., ribs, diaphragm, lungs, pleural cavity,abdominal muscles, and, chest wall, is then amplified and coarsequantized using a binary quantizer where the quantizer threshold for agiven sweep or row is based on the median value of the data set,resulting in an intermediate black and white image for each sensor 20.Depending on the specific anatomical motion selected for monitoring,other statistical portions of the data set may be selected for imagecreation. After creation of the data underlying the initial image 370, aspeckle filter is applied to the image to remove random speckle noiseand increase the sharpness of the image boundary edges 380, supportingaccurate determination of spatial change over the target range Tcomprising the interrogation volume 60 and respiratory chamber 70. Forexample, a speckle filter having a 3×3 kernel may be applied, but otherspeckle filters could be applied depending on the desired sharpness ofthe boundary edges, which would influence the accuracy of the assessmentof spatial change. The filtered quantized image is then stored 390 forsubsequent use in cross-correlation 400 with other motion detectionprocesses in the pulmonary motion determination process and algorithmillustrated in FIG. 32.

The pulmonary image quantizer algorithm illustrated in FIG. 31 causesdata from each sensor 20 to be successfully presented as an image spacefull of various spatial structures changing in time that represent bothchest wall and other motion associated with respiration along with othernon-respiratory based noise sources including other organs, bones,patient motion, and stray radiofrequency (RF) emissions. Referring nowto FIG. 32, to further refine the collected and processed data,additional pulmonary metrics are calculated and integrated as part ofthe overall method of the invention to delineate and confirm that thestructures found in the quantized image 390 are, in fact, anatomicalelements associated with respiratory functionality and not caused byother undesirable signal sources. This confirmation ensures thatmeasurements associated with these respiratory-influenced structureswill be used to determine the instantaneous respiratory volume, tidalvolume and other metrics. The data from each sensor 20 may be usedindividually or in aggregate to calculate the various pulmonary metrics.As more sensors 20 are deployed about an individual's upper body, as inany of the earlier described embodiments compromising multiple sensors20, the granularity and accuracy of the respiratory measurements can beincreased. However, the granularity and accuracy associated with the useof only a single sensor 20 may be sufficient in many cases to obtain thediagnostically-significant data to support the generation of the valuesfor the desired metrics.

FIG. 32 illustrates the process and algorithm associated with thepulmonary motion detection and selection module 400, according to anembodiment of the invention. In a first step, the motion detectionmodule 400 causes the stored image 390 produced by the pulmonary imagequantizer module 300 of FIG. 31 to be transformed to a frequency domain410. The motion detection module 400 determines the respiratory rate byconverting the entire swept image space to a predetermined frequencydomain using a Fast Fourier Transform (FFT) algorithm 410. The FFTalgorithm identifies and isolates the image region (range bin) of theswept range containing the strongest respiratory signal or peak spectralcomponent 420. Output from each sensor 20 may be used to cross-checkdata from every other sensor 20 to ensure that the respiratory rate isaccurate. Hence, by using at least two sensors 20, the apparatus 10 ofthe present invention provides a cross-check function to ensure that themeasured respiratory rate is correct. If the two sensors 20 do notreport the same respiratory rate, the invention triggers an alert tonotify the caregiver, a technician or the individual, that it appearsthat at least one sensor 20 has malfunctioned and the measuredrespiratory rate may be inaccurate. Consequently, as more sensors 20 aredeployed, it becomes easier to confirm when any specific sensor 20 hasmalfunctioned, allowing both the image quantizer module 300 and themotion detection and selection module 400 to ignore data being receivedfrom a malfunctioning sensor 20. Once the peak spectral component hasbeen determined 420, the module calculates the respiration rate 430. Therespiration rate is then used to calculate the range of lung motion 440.In an iterative process 450, the module 400 then confirms measurementsidentifying wall motion by use of both a chain coding technique 452 anda pattern correlation technique 454. The wall motion identified fromboth techniques is then cross-correlated with the earlier quantizedimage 456. The motion detection and selection module 400 then selectsthe best lung motion 460 based upon this iterative cross-correlation.Once the best lung motion has been determined, the pulmonary motiondetection and selection module 400 calculates the various pulmonarymetrics of interest including, tidal volume and other derivative metrics470. Based upon the values of the calculated metrics, the module 400then determines whether any of several actions are warranted andtriggers alerts, alarms or notices to appropriate resources for response480.

Uniquely, while confirming the respiratory rate 430, the module andmethod of the present invention also determines the depth rangecontaining the desired targeted respiratory motion, which is used in thedevelopment and assessment of additional important IRV module metrics,discussed below. As earlier discussed and illustrated in FIG. 16A, in analternative embodiment of the present invention, one or more sensors 20or antennae 30, 40 of the sensors 20 may be placed at various positionsaround the thorax and abdominal region to capture independentrespiratory rate and rhythm data derived from one or more anatomicalelements which move in correlation with the respiratory cycle, includingthe ribs, internal and external intercostal muscles, abdominal muscles,the diaphragm, lungs, and chest wall.

During the process of assessing and selecting pulmonary motion, a secondmetric developed by the pulmonary motion detection module 400 comprisesthe identification and verification of the completeness of each targetinterrogation volume 60 and the overall respiratory structure, therespiratory chamber 70, as it changes over time. As the lungs expand anddeflate in a sustained and rhythmic fashion during each respiratorycycle, the pulmonary motion detection module 400 identifies and selectscandidate signals from one or more sensors 20 for further analysis bycapturing and prioritizing signals having minimum discontinuities,suggesting the expected signal is associated with the continuousrhythmic motion of respiration. In one version, the algorithmic processof the IRV module leverages a chain coding technique 452 in conjunctionwith structural morphological techniques or pattern correlation 454 tominimize signal discontinuities caused by noise loss, such as whitenoise. Each of the chain coding and pattern correlator techniques isjuxtaposed and cross-correlated with the earlier quantized image 456.

A third metric developed by the pulmonary motion detection module 400comprises continual and repeated identification and tracking of arespiratory-like motion characteristic in the candidate image space foreach sensor 20. The desired motion characteristic best characterizes theapproximate motion of the chest walls, lungs or other targetedanatomical element with each target respiration volume duringrespiration over time. A corollary, yet opposite and equally importantcomponent of this third metric comprises the isolation and avoidance ofsignals from each sensor 20 having a motion characteristic that is notindicative of chest wall, lung or other motion derived from respiratorycycle influence. Essentially, the algorithm eliminates fromconsideration those signals that are most likely generated by anon-respiratory signal source.

A fourth metric developed via the algorithmic process and method of thepresent invention of the pulmonary motion detection module 400 is thedevelopment of a correlation between (1) the time-domain characteristicsfor each sensor 20 of the isolated respiratory range bin identified inthe first step to determine the respiratory rate metric with, (2) pointsidentified in the image space calculated for each sensor 20 thatrepresent minimum, maximum, and zero-crossing points of respiratoryexcursions in the image space of the sensor 20 encompassing therespiratory chamber, as identified by the second and third metrics,structure completeness and motion characteristics.

After processing raw data to generate results containing the abovemetrics, the image regions for each sensor 20 that meet the requirementsof the above metrics are isolated and identified as good candidateslikely indicative of respiratory motion and suitable and desirable forfurther analysis 460. Each image region is repeatedly evaluated and afinal candidate image region is selected as the truest representation ofinstantaneous respiratory volume 460. This truest representation is thecandidate having the strongest characteristics in all metrics. Thiscandidate then becomes the current “truest” candidate until it issubsequently replaced by a “truer” candidate.

With the current truest candidate chosen, the algorithm of the pulmonarymotion detection module 400 identifies and quantifies minimum andmaximum respiratory excursions using the earlier collected dataavailable from the assessment of the four key metrics discussed above.Then, with the minimum and maximum respiratory excursions determined foreach sensor 20, the algorithm of the module 400 determines the actualphysical lung displacement by measuring and counting the spatial pixelstraversed from a min-point to a max-point of the respiratory waveformand multiplying the number of pixels by the resolution of the dataacquisition device (DAQ), then aggregating and correlating the excursionfor each of one or more sensors 20 to the selected geometric model forthe lungs.

In a next correlation and aggregation step, the apparatus uses thealgorithm and calculates the instantaneous respiratory volume (IRV) bycalculating a representative volume based on the measured respiratoryexcursion distance from each sensor 20 and the defined respiratorychamber 70. This measured physical lung displacement for each sensor 20is then applied to the selected geometric model of the lungs todetermine instantaneous respiratory volume and tidal volume.

16. Software User Interface

FIG. 33 is an illustration of a user interface of the apparatus of thepresent invention, wherein the interface provides a real-time display ofboth pulmonary and cardiac rate and rhythm sensed by the sensor(s) 20.The interface allows a user to isolate and select various bins or depthsegments associated with the interrogation volume 60 and respiratorychamber 70 to manually identify those traces presenting as havingpulmonary features, or, cardiac features. The interface allows variousfilters to be applied to focus selection on either cardiac or pulmonaryinformation. In addition, the interface provides a display of real-timecardiac and pulmonary rate, along with various trend metrics. In theexample of FIG. 33, the user has identified bins 7 and 15 as havingthose features most indicative of cardiac and pulmonary behavior. Theinterface of FIG. 33 supports real-time data collection as well asreal-time algorithmic adjustment to more readily capture target cardiacand pulmonary information from each sensor 20.

FIG. 34 is an illustration of the software interface of the invention tosupport post-processing of collected data to isolate pulmonary andcardiac waveforms. This interface allows a user to perform detailedanalysis of collected data and apply one or more filtering solutions tothe method of the invention, subsequent to collection of data from asubject.

FIG. 35 is a chart produced from the software of the inventionassociated with FIG. 34 illustrating an isolated respiratory trace for aparticular bin number 15. The respiratory trace follows the shape of atypical pulmonary cycle and also includes the influence of cardiacbehavior throughout.

17. Dielectric Monitoring—Early Identification of Potential CongestiveHeart Failure

In a further embodiment, the present invention provides a novel systemand method for monitoring those persons dealing with chronic heartconditions or other diseases which may cause them to suffer fromperiodic pulmonary congestion which can ultimately lead to congestiveheart failure and death. Congestive heart failure is a seriousphysiological condition that is associated with changes in both cardiacperformance and respiratory performance. FIG. 18 is an illustration of asubject experiencing partial congestion or fluid buildup in thesubject's left lower lobe LLL. Congestion may be the result of cardiacfailure or some other condition, such as pneumonia. In one embodiment,as illustrated in FIG. 18, congestion in lungs RL, LL may be monitoredby one or more sensors 20. In a congestive heart failure monitoringmode, the apparatus 10 comprising one or more sensors 20, causes eachsensor 20 to transmit a series of interrogatory pulses S at target areasT of the lungs RL, LL. Each of the sensors 20 of the apparatus 10includes a transmit antenna 30 and receive antenna 40. The transmittingantenna 30 of each sensor 20 directs electromagnetic energy toward atarget area T in the lungs RL, LL. A portion of the transmitted energyis reflected back from the target area T as reflected signals S′ to thereceiving antenna 40, in part, due to the large difference in dielectricvalue between the air and liquid in the lungs RL, LL, along withdielectric differences in other tissues in the target range of interest.In addition to the algorithms of the present invention tuned to captureand process anatomical motion, the apparatus 10 includes an advancedalgorithm used in conjunction with one or more algorithms of therespiratory sensor module 50 for capturing dielectric information fromvarious target areas T to track changes in dielectric values in thetarget areas T during a respiratory cycle.

FIGS. 36-39 are tables of simulated dielectric values associated withmeasurement of various respiratory states, measured in an aggregatemanner or individually for each lobe of each lung. FIG. 36 is a table ofsimulated dielectric values for a subject in both a normal and congestedstate, emphasizing an aggregate basic correlation, preferably measuredusing a single sensor 20 targeted toward a lower portion of either theright lung RL or left lung LL. The lower portion of either lung RL, LLwould be targeted since congestion is frequently found to first occur inthe lowest lobes of each lung RL, LL. In the congested state, thedielectric value is higher due to the presence of additional fluids inthe lung tissue. Consequently, in a first version, the present inventionwould comprise two sensors directed to the left lower lobe LLL and theright lower lobe RLL of the subject since these lobes are most likely tofirst experience fluid build-up, indicating a trend toward congestiveheart failure.

FIG. 37 is a more detailed table of simulated dielectric values for anindividual progressing from a normal respiratory state (withoutcongestion) through to a third state of congestion, as measured at aninflated and deflated point in the normal respiratory cycle. For clarityof explanation, the simulated data tabulated in FIGS. 36-39 are shown asbeing presented only at a fully inflated or fully deflated state.However, in a preferred embodiment, the sensor 20 of the apparatus 10continuously measures the dielectric values associated with the targetedareas during the entire respiratory cycle. The data tabulated in FIG. 37is once again based on an aggregate dielectric value measured from atargeted portion of either lung RL, LL, preferably the lower portion ofeither lung RL, LL. The table of FIG. 37 tracks the cumulative averageand the cumulative dielectric values measured by a single sensor 20 overfour states from normal to full congestion.

FIG. 38 is a table of simulated dielectric values of an individualprogressing from a normal uncongested respiratory state to a third stateof congestion, wherein the dielectric value is measured by separatesensors 20 arranged to target each individual lobe of each lung RL, LL.For purposes herein, the left superior lobe is the equivalent of theleft upper lobe LUL; the left inferior lobe is equivalent to the leftlower lobe LLL; the right superior lobe is equivalent to the right upperlobe RUL; and, the right inferior lobe is equivalent to the right lowerlobe RLL. By increasing the granularity of the measurements to targeteach lobe, the apparatus 10 comprising at least five sensors 20 directedtoward each lobe can track dielectric behavior of each lobe to increasethe amount of information available to a physician, thereby increasingthe physician's respiratory knowledge specific to a particular patientand allowing the physician to evaluate the information to identifyearlier precursors of congestive heart failure. For example, afterevaluating a patient using five or more sensors 20 targeted toward eachlobe, the physician may be able to determine that a single sensor 20positioned above a particular lobe will provide sufficient informationto respond to earlier indicators of a trend toward congestive heartfailure to avoid allowing the patient to reach a state of fullcongestive heart failure.

FIG. 39 is a table of simulated dielectric values for a hypotheticalsubject progressing from normal respiration to full congestion measuredat each individual lobe, but only at a fully inflated or inspired state.

Each of FIGS. 36-39 provides data which forms the basis for subsequentFIGS. 40-43, described in greater detail below. Now, in greater detail,the apparatus 10 of the present invention obtains a measure of thechange in the bulk dielectric strength of a targeted portion of thelungs RL, LL during a respiration cycle over a period of time to developa trend which may indicate progression toward congestive heart failureor implications from other diseases known to cause fluid build-up in thelungs, e.g., pneumonia.

FIG. 40 is a chart illustrating normal or baseline dielectricmeasurements associated with each lobe at full inflation and deflationduring a normal respiratory cycle where the subject is known to not havecongestion. This baseline relationship is ingested by the apparatus ofthe present invention to serve as an anchor in determining whendeviations from this baseline are suggestive of cardiac or respiratorycomplications. Importantly, by measuring the dielectric behavior of thelungs during a respiratory cycle, the apparatus may be capable ofidentifying indicators of a trend toward congestive heart failure thatin the past have been unavailable. In the normal baseline, thedielectric value measured at each lobe of each lung is greater duringthe deflated state due to a reduction in the amount of air in the lungs.

FIG. 40 further includes two trend lines describing the mathematicalrelationship between the measured dielectric value and a lung status ateither a fully inflated or fully deflated state. The first describes therelationship for the right inferior lobe RML; the second describes therelationship based upon a cumulative average trend across all lobes. Afundament element of the method of the present invention for determiningwhether a subject may be progressing toward congestion is continuallymonitoring the subject and providing an alert whenever the readingsdeviate from the algorithmic relationship associated with respirationduring an uncongested status. The apparatus 10 will continually trackthe measured dielectric values and compare these values against multipletrend lines associated with non-congestive pulmonary performance.Although shown in FIG. 40 as providing only two trend lines, the presentinvention supports the development of a multiplicity of trend lineswhere a trend line may be developed for each lobe of each lung atdiffering levels of inflation/deflation.

FIG. 41 is a chart tracking the change in measured respiratorydielectric values during a respiratory cycle through three progressivestages toward congestive heart failure. Again these measurements aresimulated for acquisition at the fully inflated and fully deflated stateof a normal respiratory cycle, and therefore, presume a straight linerelationship between the two extremes of inflation and deflation.However, the apparatus 10 of the present invention will provide acontinuous measure of dielectric value to provide a more comprehensiveview of changes and trends in dielectric values during multiple stagesof progression toward congestion. For example, the shape of the curvebetween fully inflated and fully deflated during an entire respiratorycycle would have value to measure any breathing restrictions based uponthe shape of the curve. Additionally, the present invention is equallyadept at determining the efficacy of treatment to avoid congestion bymonitoring the dielectric values and determining that trends are headingback toward the normal baseline dielectric values.

Water is known to occupy approximately 60% of the tissue volume in anormal lung. As the lungs inflate during inspiration, additional airenters the lungs, causing the bulk dielectric constant of the targetarea of the lung to decrease, reaching a minimum at full inflation sincethe dielectric strength of typical lung tissue is greater than that ofair. As the lungs deflate during expiration, air is expelled from thelungs, and the bulk dielectric constant of the target portion of thelung increases, reaching a maximum at full deflation. For illustrativepurposes, and with reference to FIGS. 36 and 40, this relationship canbe described where, in a fully-inflated state, the targeted lung tissuehas a dielectric strength of 20 as measured by the apparatus; in a fullydeflated state, the targeted lung tissue has a dielectric strength of47. Consequently, during a respiration cycle, the dielectric strengthwill vary approximately between the two values of 20 and 47.

The variance from the minimum or maximum dielectric value at a point intime may be calibrated to establish the approximate volume of air in thelungs at any point and time during a respiration cycle. Hence, thepresent invention uses the relationship between changes in dielectricvalue as measured by the apparatus 10 and the existing volumetric modelof the lungs to determine the volume of air in the lungs at any timeduring a respiration cycle.

As indicated, the apparatus 10 of the present invention continuouslymeasures the value and difference in the lung dielectric strengthbetween peak inflation and deflation, and then establishes a measure ofthe tidal volume during a respiration cycle by correlating thedielectric difference to empirical measurements of volumetric change.Once the dielectric differences have been correlated with volumetricdifferences, the algorithm of the method of the invention creates acorrelated dielectric-volumetric curve (DVC). Referring to FIG. 40, theDVC is then used in the process to determine instantaneous lung volumeat any time during a respiration cycle. This difference measurement maybe further correlated with the mechanical motion associated with lungexcursions associated with a respiratory chamber 70 as measured by oneor more sensors 20, thereby providing a second measure and check toincrease overall accuracy of measurements. The invention then uses thesemeasurements to also provide another cross-check to tidal volume and toinstantaneous respiratory volume (IRV) determined using the previousdescribed imaging methods associated with image quantizer module 300 andthe motion detection and selection module 400.

As illustrated in FIG. 40, in a further derivative embodiment based onmeasurement of changes in dielectric strength during a respiratory cycleto assist in the early identification of congestive heart failure, thealgorithm of the method of the invention includes an adaptive functionto measure and track the value of the bulk or cumulative dielectricstrength of a target respiratory chamber over time, creating a normalrespiratory dielectric curve for the respiratory cycle of a subject. Themethod of this embodiment presupposes that a base-line or normalrespiratory dielectric curve is generated during periods of relativehealth where congestion is not present. Once this normal respiratorydielectric curve has been established, the apparatus 10 then continuesto track and monitor the dielectric strength of the targeted respiratorychamber 70 of the subject to monitor any deviation from normal status.When the apparatus 10 determines that a deviation from normal hasoccurred, the deviation is then assessed to determine potential causesfor the deviation. Alternatively, whenever a deviation from normal isobserved by the apparatus 10, an alert may be triggered requiringvarious subsequent follow-up actions or responses.

For example, in one circumstance, the algorithm of the method of thepresent invention determines whether the change in the respiratorydielectric curve is due to the buildup of fluid within the targetedportion of the lung. Abnormal fluid buildup in the lungs will cause theapparatus 10 to detect an overall increase of the measured dielectricstrength of the targeted portion of the lung, during both inspirationand expiration, shifting the entire curve upward, away from the normalbase-line position, as shown in FIG. 41. Once the apparatus 10determines that the measured data suggest the deviation from the normalrespiration dielectric curve is possibly due to fluid buildup in thelungs, the other measured physiological parameters are examined andevaluated to determine if corresponding changes have occurred thatsuggest a trend toward, or, the onset of, congestive heart failure. Thechange in fluid content parameter is juxtaposed against trends andchanges in cardiac rate and rhythm, stroke volume, respiratory rate andrhythm, and tidal volume, among others, to help determine whether thesymptoms suggest the onset of congestive heart failure, therebyproviding a real-time early warning system to allow treatment at theearliest stage possible.

FIG. 42 is a chart illustrating respiratory dielectric progressionduring stages of congestion for each lobe of each lung along with thedevelopment of trend indices for both the right and left inferior lobesRLL, LLL, as measured and calculated by the present invention. The rightand left inferior lobes RLL, LLL were chosen for assessment and trenddevelopment in this case since the lower lobes tend to present withcongestion earlier than the middle or upper lobes. The data for thechart is based upon simulation of data collection from five sensors 20placed on an individual's chest and thorax in both an inflated anddeflated state through four stages progressively moving towardcongestion. In this simulation, the dielectric progression for the leftinferior lobe LLL is described by the LIL Index described by thepolynomial equation:

y=−0.5893x ²+11.935x+17.696

-   -   where y is the dielectric value; x is the stage of congestion.

Consequently, the present invention would track the dielectric value forthe right inferior lobe RLL and continue to compare the measureddielectric value against the trend index. Based upon the measureddielectric value, the apparatus would determine what stage of congestionis being experienced by the patient. Depending on the stage ofcongestion, various responses would be triggered by the apparatus. Forexample, a first stage of congestion might trigger an alert to take adiuretic of some sort to reduce fluid.

A second stage alert might trigger an alert to advise the patient tocontact their physician for additional guidance. A third stage alertmight trigger an alarm sent to the patient and others to direct thepatient to reach an emergency room as soon as possible. Other triggersand associated alerts can be incorporated in the algorithms to allowadditional desired actions and responses driven by the measureddielectric values and assessment of overall congestion as determined bythe dielectric progression curve, i.e., the dielectric progression trendindex for a particular lobe.

FIG. 43 is a chart illustrating the ability of the present invention totrack and trend the dielectric behavior of each lobe of each lungsimultaneously. As illustrated, the present invention generates a trendindex for each lobe such that the progression of congestion in each lobemay be monitored and used as part of the clinical evaluation of apatient. For example, the present invention supports the incorporationof alarms where the congestion might present in any of the five lobes.Each of the dielectric progression curves may be consulted and readingsfrom each sensor 20 for each lobe may be compared against theirrespective dielectric progression curves. For example, in the case wherea subject may be experience some level of congestion in a left lowerlobe LLL but not in the right lower lobe RLL, a physician may elect todelay treatment since there is only evidence of congestion in the leftlower lobe. Consequently, if only one sensor 20 were used on the leftlower lobe LLL, and the readings indicated a progression towardcongestion, more drastic action might be taken to seek help to addressthe congestion.

In a further version, the present invention supports the juxtapositionand comparison of measured change in dielectric value against data fromother sensors, such as a pulse oximeter. For example, upon determiningthat the measured dielectric values suggest a trend toward, or onset of,congestive heart failure, the measured oxygen saturation provided by thepulse oximeter may be assessed. If pulse oximeter indicates that oxygensaturation is low or dropping, this would further reinforce theindications provided by the apparatus 10 via measurement of dielectricvalue.

The ability of the apparatus and method of the present invention toprovide early identification of potential progression toward congestiveheart failure will substantially improve a caregiver's ability tomonitor an at-risk individual. This capability will dramatically reducethe mortality rate normally anticipated with the onset of congestiveheart failure. The symptoms will not be overlooked simply because thesubject is not adequately and constantly monitored. Those individualspredisposed to congestive heart failure do not always have access to ahospital or clinical facility where more complex and sophisticatedsystems can be used to determine the onset of congestive heart failure.

This capability would also be invaluable in helping to diagnosispotential heart problems where the condition develops over a longerperiod of time, and hence, would not be as noticeable. For example, forthe ambulatory individual in a home setting, the typical methods used todetermine whether an individual might have symptoms indicative ofcongestive heart failure are extremely rudimentary, qualitative andimprecise, and therefore, likely to place a subject prone to congestiveheart failure at greater risk for not detecting onset of congestivefailure. For example, current methods recommended by physicians requirethat an individual weigh him or herself on a periodic and regular basis,to determine if there is an abnormal amount of weight gain, suggestingfluid buildup. One approach is to weigh each morning and night.Unfortunately, this period is sufficiently long that an individual couldsuffer from congestive heart failure during the period betweenweigh-ins. Additionally, if an individual had a fairly large meal, theadditional weight gained might be perceived as simply a result of theexcessive indulgence, when in reality, a portion could actually becaused by pulmonary congestion.

Another existing method used to assess the potential onset ofrespiratory and cardiac congestion is to measure the number of pillowsused during sleep. While sleeping, an individual will monitor the numberof pillows required to create a sufficiently comfortable position toavoid breathing complications. If additional pillows are required, thismay indicate fluid buildup in the subject's lungs and potential onset ofcongestive heart failure. As can be appreciated, this method is veryqualitative, subjective and depends on the patient to determine whetherproblems are developing.

Additionally, another existing monitoring method is for the patient tomonitor the size of his or her lower extremities by measuring orobserving the circumference or skin tension of the legs and ankles todetermine if there is any potential swelling, which might also suggestfluid buildup and indicate potential onset of congestive heart failure.Again, this approach is qualitative in nature and relies on theassessment of the patient.

As described above, when sophisticated monitoring is unavailable in anat-home setting, the patient is expected to monitor weight fluctuations,the number of pillows required to sleep comfortably, and, swelling inthe legs. Unfortunately, these are gross qualitative measures that firstpresume the at-risk individual is actually capable of accuratelymonitoring these parameters. If the particular individual has othermedical complications, such as Alzheimer's, short term memory loss orother dementia common in elderly patients or patients experiencingoxygen deprivation due to congestion, it is unlikely they will have theability to accurately monitor these parameters without caregiverassistance and follow-up. They will be unable to stay abreast of theirmedical condition and determine when additional treatment is indicatedto mitigate the affects of fluid buildup, without the assistance of acaregiver. Consequently, the present invention provides a moredefinitive, simple, reliable and accessible means to monitor forpotential heart failure while avoiding the failings of the otherexisting qualitative methods described above. The present inventionprovides a simple medical device that can independently monitor precise,quantitative parameters indicative of congestive heart failure, and,relay those measures to a more qualified individual capable oftriggering a treatment response when indicated, or, at a minimum, relaythose measures to the patient so that the patient can confidently andquickly seek additional assistance and care from their physician oremergency room, if necessary. This increased confidence in measurementwill allow a physician to more readily diagnose and treat the patient.This increased confidence in measurement will also reduce the stress apatient experiences when unable to determine whether he or she isactually experiencing pulmonary and cardiac problems. Hence, the presentinvention will reduce the number of unnecessary visits to a patient'sphysician which are caused by the patient's concern that perhaps theyare trending toward congestive heart failure. Likewise, the presentinvention will expedite treatment when necessary since the respondingphysician will have greater confidence in the quantitative measuresprovided by the various embodiments of the present invention as comparedto the qualitative assessments provide by the patient.

18. Respiratory Chamber Excursion Measurement

Now, in greater detail, the process for measuring respiratory chamberexcursion and associated tidal volume is described. The apparatus andmethod of the present invention comprises a novel medical imagingarrangement where analog assessment approaches are combined with UWBradar in estimating volumetric changes associated with a targetedrespiratory chamber 70 and therefore, assessing overall respiratoryperformance via the development and calculation of various respiratorymetrics and parameters. According to a preferred embodiment of thepresent invention, as illustrated in FIG. 4, FIG. 16A and FIG. 16B, theapparatus 10 collects reflection data S′ from one or more target areasT, associated with a selected respiratory chamber 70 encompassed by aninterrogation volume 60.

19. Identification of Respiratory Disturbances or Events

The present invention provides respiratory information that is used todetect a significant respiratory disturbance and to detect suspiciousdeviation from normal respiratory trends over time. Following is adescription of an embodiment of the method of the present invention usedto identify respiratory events.

FIG. 4 provides an illustration of the basic operation of the apparatusand method of the present invention. First, a physiological signal thatvaries with a patient's respiration cycle is monitored using theapparatus 10 comprising a sensor 20 having a transmitter 30 and receiver40. Monitoring by the sensor 20 may be either continuous or on aperiodic or triggered basis. As will be described, the apparatus 10processes, stores and/or transmits sensed signal data. A physiologicalsignal received is at least a measurement of respiratory-induced motionwithin the thoracic or abdominal cavity from which respiration rate andrhythm or other pulmonary metrics may be determined for calculating,among other things, tidal volume, total lung capacity, and volumetricoutput. The physiological signal is either a direct measurement of lungmotion or other associated anatomical features that include variationsdue to the respiratory cycle. The physiological signal may also be ameasure of dielectric strength within a targeted portion of a lung. Thephysiological signal may be either a measure of change or an absolutevalue. The physiological signal may be obtained along with otherphysiological signals such as cardiac rate, cardiac rhythm, cardiacstroke volume, blood oxygen saturation, blood pressure and thoracic orcardiac electrical activity.

The method of the present invention is implemented in the externalsensor device 20 or in an external device capable of receiving sensedsignal data from the external sensor device 20 via a telemetriccommunication link. First, parameters indicative of the patient'srespiratory activity are derived from the sensed signal. Preferably, atleast a respiration rate is determined. Additionally, other respirationparameters, such as tidal volume or peak amplitudes associated with therespiration cycle, may be determined.

At a next decision step, the measured respiration parameters arecompared to predetermined criteria for detecting a respiratorydisturbance or deviation from a respiratory trend. Such criteria mayinclude at least a respiration rate, a tidal volume, or a dielectricvalue such that when the respiration rate, tidal volume, or dielectricvalue is less than or greater than a normal range or crosses a detectionthreshold, a potential respiratory disturbance is detected at a decisionstep and labeled as a suspicious event. At a storage step, measurementsof the suspicious respiratory disturbance are determined and stored.Such measurements preferably include at least the duration of thedisturbance. At an alert step, detection of the respiratory disturbancemay optionally trigger a warning to medical personnel, the delivery of atherapy, and/or the storage of physiological data in the apparatus.

In one embodiment of the present invention for monitoring respiratorydisturbances based on ultra-wideband (UWB) sensing, a reflected UWBsignal S′ is received, and the tidal volume and respiration rate andrhythm are derived from the UWB signal, which may be used forcalculating respiratory output.

At a next decision step, one or more predetermined criteria fordetecting a respiratory disturbance are applied to the measured tidalvolume and/or respiration rate and rhythm. Predetermined criteria mayinclude comparing a given respiration parameter to a minimum or maximumthreshold. If criteria for determining a respiratory disturbance are notsatisfied, the method returns to continue monitoring the UWB signal. Ifdetection criteria are met, a respiratory disturbance is detected.Measurements of the disturbance may then be made, preferably includingat least the duration of the disturbance. The duration of thedisturbance may be an apnea/hypopnea length or hyperpnea lengthdetermined as the number of device clock or timer cycles during whichcorresponding detection criteria are satisfied. The duration is thenstored, along with other relevant data including a time and date labelto indicate when the detection was made. At a next step, a counter fortracking the number of detected respiratory disturbance episodes isincreased by one. An optional warning or alert to medical personnel byan external device or triggering of a therapy delivery or data storageby another external device may then be generated. A triggered therapymay be, among other things, cardiac pacing, delivery of apharmacological agent, insulin delivery, stimulation of the upper airwaymuscles, the diaphragm, or other electrical stimulation of the centralnervous system, peripheral nerves or smooth or skeletal muscle. Themethod is continually repeated to continue monitoring for respiratorydisturbances.

Additional details regarding methods for determining metrics ofrespiratory disturbances in one embodiment of the present invention areprovided. Upon detecting a respiratory disturbance, it may be desirableto determine various metrics of the disturbance in order to assess theseverity of the disturbance and/or track changes in these metrics overtime as a way of assessing relative improvement or worsening of theassociated pathological condition. First, an UWB signal input isreceived and used for determining tidal volume, respiration rate,absence of respiratory movement or dielectric value. Next, the derivedtidal volume, respiration rate/rhythm, absence of respiratory movementor dielectric value is compared to a predetermined apnea detectionthreshold, hyperpnea detection threshold, or dielectric threshold. If athreshold crossing is detected, a respiratory disturbance is detected,and the time of the onset of the disturbance is flagged.

The method continues to iterate and receives a next UWB signal. Themethod continues to monitor the respiration parameters until thedetection criterion is no longer satisfied. If a respiratory disturbanceonset has been flagged, as determined at a preceding decision step, therespiratory disturbance offset is flagged. If the detection criterion isnot satisfied, and no onset is flagged, then method continues to iterateand receives a next UWB signal to continue monitoring respirationparameters. After flagging the onset and offset of a respiratorydisturbance, such as an apnea or hyperpnea period, or, a congestionperiod as determined by a dielectric value, the length of the apnea,hyperpnea or dielectric congestion period is stored as the differencebetween the flagged onsets and offset.

Next, the method determines if a previous apnea episode has beenrecently detected, which could indicate the presence of a repetitivebreathing pattern. Repetitive apnea-hyperpnea or hypopnea-hyperpneaalternation is typical of certain pathological breathing patterns suchas sleep apnea and Cheyne-Stokes breathing. If this decision step isaffirmative, a periodic breathing cycle length is determined and storedas the time between onsets of two consecutively detected apnea episodes.A respiratory disturbance episode counter is then increased by one foreach disturbance detected. Depending on the type of pathologicalbreathing pattern being monitored, a disturbance that would increase theepisode counter may be a single apnea, hypopnea, or hyperpnea event ormay be a complete apnea-hyperpnea or hypopnea-hyperpnea cycle. Next, awarning to alert medical personal, to wake up the subject individualand/or to trigger a therapy delivery and/or data storage trigger may begenerated.

In a further alternative embodiment, a method for monitoring forrespiratory disturbances or trend deviation is provided. Alternativeembodiments may detect pathologic breathing patterns by determining apatient's respiration rate from any physiological signal measurable withthe apparatus that includes variations due to the influence ofinspiration and expiration, such as a cardiac signal. First, aphysiological signal input is received. A physiological signal thatincludes respiration related variations may be, but is not limited to, acardiac signal. Next, the patient's respiration rate is derived from thecardiac signal. The sensed signal may be filtered to remove higherfrequency components and pass low frequencies associated with therespiration cycle to establish a respiration rate. A preferred methodfor deriving the respiration rate comprises a simple peak detectionalgorithm. In this case, an input UWB signal measures excursion in theabdominal or thoracic region of any feature which has variability causedby the respiration cycle. By detecting individual breaths and relatedpeaks and valleys of the UWB signals, respiration rate can be derived bymeasuring the interval between peaks and tidal volume may be derived bymeasuring peak to peak amplitude change from a peak to the correspondingvalley.

The derived respiration rate is compared to predetermined criteria fordetecting a pathologic respiration rate. For example, predeterminedrespiration rate criteria may define a rate limit or zone that isindicative of Kussmaul breathing, which is more closely related to tidalvolume, Cheyne-Stokes breathing, apnea, asthma, or other respiratorydisturbances. The onset and offset of a detected respiratory disturbanceare flagged, allowing the duration of the disturbance and the cyclelength of a periodic breathing cycle to be determined and stored. Arespiratory disturbance episode counter is increased, and a responsiveaction or no action is taken.

20. Parameter Cross Check and Confirmation

A further alternative embodiment of a method for monitoring forrespiratory disturbances includes a parameter cross-check. The parametercross-check assists in confirming a suspected respiratory disturbanceprior to detecting the disturbance. A parameter cross-check may employthe signal from an additional UWB sensor or sensors for verifying thatmodulation of the primary physiological signal used to detect therespiratory disturbance is indeed due to respiration and not othermotion or factors. In one embodiment, a UWB sensor tracks body motion toverify that the signal variations extracted from the primary signal arenot due to changes in body motion. Alternatively, a separate sensor,such as an oxygen saturation sensor, may be monitored and compared tothe UWB signal outputs to confirm trends that point to a respiratorydisturbance. For example, in the case where a subject's breathing ceasesor is spotty, the subject's oxygen saturation will decrease according tothe breathing pattern.

In another embodiment, one or more physiological signals arecontinuously monitored for detecting a respiratory disturbance accordingto the methods described above. Physiological signals indicative ofheart function may additionally be monitored and juxtaposed againstphysiological signals indicative of respiratory function. If arespiratory disturbance is detected and determined to be a periodicbreathing pattern, metrics of the periodic breathing pattern aredetermined. If not, the method returns to continuous signal monitoring.These periodic breathing metrics can be correlated to cardiac functionand be used as cross-checks against metrics developed using UWB cardiacsignals. Trends of these periodic breathing metrics are determined andstored for display in various formats. A change in cardiac output may beestimated based on respiratory disturbance metrics. These data may bedisplayed for review by a physician such that worsening or improvementin respiratory or cardiac condition can be observed. Thus, detection andevaluation of disordered breathing patterns may be used for assessing apatient's cardiac condition and vice versa. If the method is implementedin association with an implantable device capable of delivering a heartfailure therapy, a worsening or improvement in cardiac output mayoptionally automatically trigger an appropriate delivery, withholding,or adjustment of therapy to the patient.

21. Implantable Sensor

As indicated above, the present invention preferably employs an externalsensor 20 for chronic respiration monitoring. The methods describedabove for detecting a respiratory disturbance may be fully incorporatedin an external device in association and communication with one or moreexternal sensors 20. Alternatively, an algorithm for detecting arespiratory disturbance and measuring characteristics of a respiratorydisturbance may be implemented in an implantable sensor in telemetriccommunication with the external device associated with the implantablesensor, in which case the external device serves primarily, for thepurposes of the present invention, for storing chronic sensor signaldata and/or transmitting the data to an additional external data storageand processing or communication device, such as a network server.External sensor (s) deliver received signals via appropriate lead (s),conductor (s) or wireless links to signal conditioning circuitry of anexternal device. Implantable sensor (s) may be located externally to thedevice but within the body of the patient or internally to the device.In addition to the UWB sensors, others sensors, including electrodes,may be integrated with the apparatus to provide sensing for an ECG, EMG,or diaphragmatic EMG signal, electrodes for sensing thoracic impedance,a blood pressure sensor, an activity sensor, an oxygen sensor, or anyother sensor that is expected to provide a variable signal containinginformation related to a patient's respiration pattern to provideconfirmatory information. Multiple sensors containing respiratoryinformation may be included. Further, where an implantable device isused, additional physiological sensors may be present such astemperature sensors, pH sensors, or any other sensors of signals ofinterest.

The signal conditioning circuit provides filtering, amplifying,rectifying and other conditioning for sensor signal input as necessaryto eliminate noise and signal components unrelated to respiration.Additional signal conditioning circuitry may be included in theapparatus if sensed signals are used for other functions other thandetection of respiratory disturbances. For example, an ECG signal may befiltered by signal conditioning circuit for extracting a respirationrate, and the ECG signal may be used by other circuitry for detectingheart rhythm. In another example, a blood pressure signal may befiltered by the signal conditioning circuit for deriving a respirationrate, and the blood pressure signal may be used by other circuitryincluded for monitoring a patient's cardiac function.

When respiration disturbance detection methods described herein areincorporated in the internal device, the output from the signalconditioning circuit is provided as input to an analog-to-digital (A/D)converter which then provides input to a respiratory disturbancedetector. Output from the A/D converter may also be provided directly todata storage memory for storing digitized signal data that may beuplinked to an external device through a telemetry link. Communicationsystems for use with implantable devices are known in the art. Thedetector may perform additional signal processing to derive signalfeatures of interest, such as respiration rate, and perform the methodsdescribed above for detecting a pathological respiration pattern. Thedetector is preferably implemented as programmable software stored inthe memory of a microprocessor. Alternatively, the detector may be inthe form of dedicated digital circuitry. The microprocessor includesmemory for storing executable programs for controlling and executingvarious apparatus functions.

If a respiratory disturbance is detected by the detector, according tothe methods included in the present invention, other apparatus functionsmay be triggered such as the storage of physiological data in memoryand/or the delivery of a therapy from a therapy output controller.Stored data may include measurements of the respiratory disturbance,time and date information relating to when the disturbance was detected,the number of disturbances detected, updated trends of respiratorydisturbance metrics, as well as other data based on other sensor input,such as ECG or EGM, blood pressure, oxygen saturation, activity, and soon.

Thus, the apparatus may be provided as an implantable recording devicecapable of monitoring physiological signals and storing physiologicaldata upon a triggering event.

Physiological data and respiratory disturbance metrics stored in datastorage memory may be uplinked to an external device through a telemetrylink. Stored data may then be displayed on a display for review by aphysician. The internal apparatus and sensor may be a minimallyinvasive, subcutaneous system. Internal apparatus and sensor (s) mayalternatively be a relatively more invasive system with sensor (s)implanted submuscularly, intramuscularly, along or within the vascularsystem, within the thoracic cavity, heart, airways or other internalbody locations appropriate for receiving a signal variable with thepatient's respiration cycle. A system including a chronically implantedblood pressure sensor and processing element is generally disclosed inU.S. Pat. No. 5,758,652 issued to Nikolic, incorporated herein byreference in its entirety.

22. Therapy Delivery Control and Feedback

Where the apparatus includes therapy delivery capabilities, a therapyoutput control delivers a therapy in response to the detection of arespiratory disturbance. Such therapies may include cardiac pacing,neuromuscular stimulation, stimulation of the central nervous system,delivery of a pharmacological or biological agent, or other therapy.Thus, the apparatus may be embodied as a cardiac pacemaker, implantablecardioverter defibrillator (ICD), neuromuscular stimulator or other typeof electrical pulse generator, implantable drug delivery device or othertype of therapeutic, implantable device. Examples of implantable devicesthat include therapy delivery capabilities in which aspects of thepresent invention could be implemented include: a cardiac pacing devicefor managing sleep apnea generally disclosed in U.S. Pat. No. 6,126,611issued to Bourgeois et al., a medication infusion system generallydisclosed in U.S. Pat. No. 4,373,527 issued to Fischell, an implantabledrug delivery system generally disclosed in U.S. Pat. No. 6,471,689issued to Joseph et al., and a device for stimulating upper airwaymuscles for treating obstructive sleep apnea generally disclosed in U.S.Pat. No. 5,540,733 issued to Testerman et al., all of which patents areincorporated herein by reference in their entirety.

Thus, aspects of the present invention may be readily implemented inimplantable devices already having an appropriate signal sensed forother device functions and which may also be used for determiningrespiration parameters. Patients having such devices may receive greaterbenefit by the added detection of respiratory disturbances when theyoccur.

Signal data stored in memory directly from the A/D converter may beuplinked to an external device. As an alternative to performingrespiratory disturbance detection online or in real time within theinternal apparatus, stored signal data may be post-processed by theexternal device. The external device is preferably amicroprocessor-based device, which may be better able to accommodatecomputationally-intensive algorithms than an implantable device forextracting respiration data from a sensed signal and for processing suchdata for the detection of pathologic patterns and for measuringcharacteristics of such patterns. The external device may be embodied asa logic device and programmer known for use with implantable,programmable devices for programming operational parameters into theinternal apparatus and for receiving stored data or other operationalinformation from the implanted apparatus. The external device mayalternatively be in the form of a personal computer with an addedtelemetry interface for communicating with the internal apparatus. Whenembodied as a programmer, the external device may receive stored signaldata and save it in a format that may be transferred to a personalcomputer for further processing or by internet to a central patientmanagement network. A bi-directional communication system that isnetwork, Internet, intranet and worldwide web compatible to enablechronic monitoring based on data obtained from implantable monitors isgenerally disclosed in International Publication No. WO 01/70103 A2,issued to Webb et al, incorporated herein by reference in its entirety.

A respiration disturbance detector may be included as an executableprogram in the microprocessor of the external device. The detectordetects respiratory disturbances offline, using methods describedherein, from stored signal data uplinked from the internal apparatus. Ifa pathologic breathing pattern is detected, a clinician alert may begenerated, which may be an audible and/or visual notification displayedon a display with supporting data. The alert may also be in the form ofa phone call or page to one or more remote or local locations, includingcell phones, PDA's or pagers. Metrics of the detected disturbances arepreferably displayed on the display.

An oximeter for measuring blood oxygen saturation may be provided as animplantable sensor or as an external sensor and used to cross-checkreadings from the sensors 20 of the apparatus 10. Therefore an oximetermay be included in implanted sensors and provide oxygen saturation datadirectly to the internal implanted apparatus 10. An oxygen saturationsignal may then be used as a cross-check parameter in response todetecting a respiratory disturbance. The oxygen saturation signal mayadditionally be the primary signal used by the respiratory disturbancedetector for measuring the patient's respiration rate for detectingrespiratory disturbances. Alternatively, an external oximeter may beprovided for measuring blood oxygen saturation. An external oximeter maybe placed at various body locations but is preferably placed on afingertip or ear lobe. The oxygen saturation signal may be received bythe external device and may under go filtering, amplification or othersignal conditioning and digitization. The oxygen saturation signal canbe down-linked to the internal apparatus via a telemetry link such thatwhen the internal apparatus detects a respiratory disturbance, theinternal microprocessor can confirm the respiratory disturbance viacross-check with the oxygen saturation parameter.

Thus, an apparatus and method have been described for monitoringrespiration and detecting respiratory disturbances that are related to apathological condition. While specific embodiments have been describedherein, it is recognized that variations of the described methods fordetecting respiratory disturbances, measuring characteristics of thedisturbances, and storing and displaying respiratory disturbance datawill exist. The embodiments described herein, therefore, are intended tobe exemplary, not limiting, with regard to the following claims.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

The present invention has been particularly shown and described withrespect to certain preferred embodiments and features thereof. However,it should be readily apparent to those of ordinary skill in the art thatvarious changes and modifications in form and detail may be made withoutdeparting from the spirit and scope of the inventions as set forth inthe appended claims. The inventions illustratively disclosed herein maybe practiced without any element which is not specifically disclosedherein.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. Furthermore, no limitations are intended to thedetails of construction or design herein shown, other than as describedin the claims below. It is therefore evident that the particularembodiments disclosed above may be altered or modified and all suchvariations are considered within the scope and spirit of the invention.Accordingly, the protection sought herein is as set forth in the claimsbelow.

What is claimed is:
 1. An apparatus for determining a change in thespatial configuration of a lung by interrogating the lung withelectromagnetic energy, comprising: at least one antenna adapted to belocated adjacent a portion of the lung; and a sensing unit capable ofresolving a change in reflected signals, wherein said sensing unit ofthe apparatus is capable of resolving a change in reflected signals thatare functionally related to a change in respiratory volume.